At the time, a silver groat would have been enough to buy a sheep
A hoard of silver coins hidden in a Northamptonshire field during the Wars of the Roses is expected to fetch more than £30,000 at auction in December.
The 290 silver groats were found in a field in Brackley in 2005 by a man using a metal detector.
It is thought they were hidden in the summer of 1465 by someone who went into hiding during the dynastic civil war.
Jeremy Cheek, from auctioneers Morton and Eden, said the coins represented a "sizeable stash of money" at the time.
He said the groats - fourpenny pieces - dated mostly from the reigns of Henry V (1413 - 1422) and Henry VI (1422 - 1460) and were relatively free from corrosion but were worn from being in circulation.
Mr Cheek said: "When they were in circulation, a silver groat would have been enough to buy a sheep.
"As there are no gold coins in the hoard, it does not appear to have been the property of a particularly wealthy person."
He said the groat was the largest silver coin of the time and could be equated in value to a £20 note.
The man who found the coins, after asking permission from the landowner, said: "I was amazed. They were lying there about a foot below the surface."
The hoard will be auctioned on 2 December.