They're shiny, brown and loads of fun, but soon there may not be many conkers around, because a disease is attacking horse chestnut trees.
So we wondered if YOU'VE noticed anything different about conkers this year - have they fallen from the trees earlier, or perhaps they're not as big and hard as usual?
And how bonkers are YOU about conkers?
Do you play loads of cool games with your mates, or maybe they've been banned at your school?
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"Near my swimming pool there's a conker tree. The conkers on it fell down earlier this year, and they were really soft and small."
Elissa, 8, Nottingham, England
"I haven't actually had a conker before, but when I used to be in primary lots of people used to bring them in and show them. They looked quite cool, but now they have banned them and they used to be lots of fun :("
Henna, 13, Glasgow, Scotland
"On a chilling night in late September, Alex, Frankie and Ella set out on their conker mission. They started the night with a girly night in and soon they had left to go on an epic search for the WORLD'S BIGGEST CONKER. After hours and hours of searching we soon came across a conker the size of an apple! It was incredible! I have never seen anything as immense as this!"
Ella, 14, Manchester, England
"Me and my dad were walking in a park and found eight conkers. Four of them were cracked and had goo coming out of them and the others were cracked. It was really weird."
Emma, 10, Liverpool, England
"I used to love picking conkers at primary school, but I don't anymore because once I brought them home and left them for ages, and then they got all maggoty. Ewww! I havn't played with them since!"
Namra, 11, Aldershot, England
"The conkers on my drive are really big!!!! But the tree doesn't look good."
Nina, 8, Nottingham, England
"Last year I go 100 conkers and it filled lots of bags but this year they were tiny and rotten when they came out and I only got 40. That's a big change for one year."
Alana, 11, Dunfermline, Scotland
"The tree near me has quite big conkers, but not that big. It's so unfair. :("
Fiona, 10, England
"This year the conkers have turned out to be smaller than usual and I USUALLY collect the best looking big ones but I haven't been able to."
Clara, 12, Middlesex, England
"It's very strange because I have actually noticed the conkers coming very early this year! Everyone is rushing round with plastic bags trying to find the biggest one but they are all tiny!"
Kim, 12, Crowborough, England
"Me and my friend found 349 conkers one day! See if you can beat that!"
Alice, 11, Northampton, England
"Where I live more conkers are falling but they're just too small. Our school has now cancelled our conker contest."
Josh, 12, Clwyd, Wales
"I really don't see what the big deal is about conkers. All they do is hurt people in tournaments and matches. I think that people shouldn't muck around with conkers in case they get hurt."
Alysha, 12, Crawley, England
"I think people are picking them too soon, because when you crack the shell open the conkers are only very small."
Hannah, 10, Liverpool, England
"This year me and my friend Eloise are very upset that the conkers are smaller!"
Zoe, 7, Somerset, England
"Over the road from my nan's house there is a conker tree, but there were no conkers on it!! I found a measly one conker and it was really small."
Amber, 12, Kent, England
"I used to go conker picking every week but now I can't go any more."
Thomas, 8, Grimsby, England
"At my new secondary school we have a massive conker tree where every year there are more than 600 conkers. This year I can tell there are less than a quarter of that. They are all tiny, literally about the size of a teaspoon, what's going on?"
Chloe, 12, Bristol, England
"I like playing and collecting conkers but I am not really bothered that the conkers are much smaller."
Sarah, 10, Clackmannanshire, Scotland
"The conkers are all small and mostly cracked around where I live. I've only found two good big ones, but last year I found 16 - so I've found 14 less!!!"
Brett, 11, Hereford, England
"I love conkers, and have noticed there are less conkers this year. Now that I know about the disease, I will keep the conker I found at my school because it is nice and shiny and smooth and bright."
Hannah, 12, Peterborough, England
"I haven't really paid much attention to the conkers, I like their shininess but I'm not really fond of playing the games."
Sophie, 12, Eastbourne, England
"We have a very large conker tree in our garden and we have had loads of shiny large conkers, they started falling in August, hopefully it won't effect us."
Megan, 11, Overbury, England
"He He! This is a real funny story! Me and my brother were looking for conkers and my brother is five years old. He picks one up and says to me 'Georgia! Quick, Quick I found one!!'
So I go up to him and look at it. I said to him 'Well done, Tom!' . As I went to search some more I heard a crunching noise behind me. I turned around to see that my brother had EATEN the conker!!!"
Georgia, 11, Aberdare, Wales
"When me and my family went to Alexandra Palace we found 30 of them."
Millie, 8, London, England
"I think last year the conkers were much bigger than this year."
Wiktoria, 10, Nottingham, England
"I hate conkers!!!!!!!!!!!!!!"
Sam, 8, North Yorkshire, England
"I love collecting conkers in my back garden but now the tree's got a disease. One day I knocked a big one off and there was nothing inside it!!!!!!!!"
Daniel, 10, Manchester, England
"Everyone at my school is throwing things into the tree to get the conkers down. This happens every year, even 1 person chucked their school show up and lost it up a tree."
Amy, 10, Nottinghamshire, England
"I have a horse chestnut tree hanging over my garden and some of its conkers look really big, especially the ones that are still hanging!"
Kane, 11, Newbury, England
"2 years ago I got 208 conkers but this year I only got 40!"
Emily, 8, Altrincham, England
"The conkers this year around my school are huge but falling really quite early and are still sometimes green when we find them. Please remind people not to leave them around because my dog ate one last year and it stuck in his stomach. He had to have an operation to have it taken out and he was really sick."
Archie, 8, Chichester, England
"Because of global warming, the conkers are coming out smaller, softer and WAY too early. I'm getting really concerned about the Earth :)"
India-Mae, 11, London, England
"I think that it's the right thing for conkers to not be around anymore because if the disease is attacking horse chestnut trees, it's sort of damaging the environment."
James, 9, Essex, England
"We have conkers at the bottom of our garden and we went down and they're all dried up and very small but that's a couple of them not all of them."
Rebecca, 11, Midlothian, Scotland
"Me and my friends all go collecting conkers after school and we have noticed that this year they have fallen a lot earlier and we have found very few big ones."
Katie, 9, Horsham, England
"I think conkers are too small and coming a bit too fast. Every morning I go to high school I see lots of small ones but not big."
Jessica, 11, Manchester, England
"I remember when I used to do a conker tournament at school and the winner got everyone's biggest conkers!!!"
Aisha, 11, High Wycombe, England
"At school, we have to bring in a yogurt carton and a conker, because all of us are going to plant some. :)
Adam didn't take in one yet, though he did take in 4 conkers, and the 2 of us and the rest of our table were messing about with them. Paul coloured one in yellow, and the rest of us used our pencils to crack one open! It was great fun!"
Justine, 9, County Louth, Ireland
"Each year me and my friends collect conkers but this year me and my friends have noticed that they have got a lot smaller. So we can't play conkers."
Hannah, 10, Frome, England
"I went conker hunting with my dad and brother, and we couldn't find a tree that had any conkers on it."
Jack, 12, Gloucestershire, England
"I love to collect conkers. Every autumn me and my family go conker hunting at our local park but they do actually seem to be getting smaller."
Jessica, 11, Tunstall, England
"I have loads!!!!!!!!!!"
Philip, 9, Cardiff, Wales
"I have a couple of conker trees out the front of my house. Every year, me and my sister collect as many as we can, then choose two out and have a mini conker championships. When the conkers started falling in July, we thought something may be wrong! We also realised that they were much, much smaller than usual. The biggest one we got was just a little bigger than a small grape! :("
Charlotte, Woking, England
"In my school there are lots of conkers on the floor, they are so soft that someone threw one and it smashed."
Amy, 11, Dagenham, England
"I think that conkers this year have fallen too soon and because of that they are too small to play with. Because of that there will probably be no competition this year."
Joshua, 10, Lancashire, England
"Whilst I was in Germany at the start of September, a conker hit me on the head, loads were falling!!"
James, 13, Kings Lynn, England
"Less conkers and smaller. The leaves are looking sick."
Oscar, 5, Essex, England
"Around my area the conkers have come early and are either dying or small, probably because of the bad summer. I've even found one with half the shell missing."
Charlie, 11, Leicester, England
"My friend brought a conker into school the other day and it was huge. I haven't noticed any change. They are still fun and enjoyable."
Amy, 11, Liverpool, England
"I really love conkers, I always collect them every year. They are fun to play with and you can do loads of things with them."
Celina, 12, Birmingham, England
"Conkers in my area are either falling off too early or they split into three sections."
Chloe, 9, Hampshire, England
"I think the conkers are a lot smaller and the spikes are not as sharp this year."
Lewis, 12, Worcestershire, England
"Near where I live there has been more conkers!!!!!!!!!!!!!!!!"
Chelsea, 11, Surrey, England
"I really love collecting conkers when they're out because my granddad put holes in them and me and my brother play with them. I always win though!"
Georgia, Warrington, England
"We have noticed that the conkers are smaller, dry and more cracked than they were last year. They are also dull."
Knighton House School, 9, Dorset, England