A handful of ancient Roman coins have been dug up in a playing field in West Wickham, near Bromley, south London.
The coins were found alongside the route of a dried-up stream
The artefacts may have been thrown into water for good luck by superstitious Romans, an archaeologist suggested.
They were discovered at the Sparrow's Den field during work by Thames Water to reduce flooding risk from sewers.
The low denomination coins, two of which depict Roman emperors Constantine and Diocletian, are said to date back to the Third and Fourth Centuries.
The artefacts were found together with two Georgian coins, a medieval silver penny and military badges from World War Two.
They were discovered alongside the route of a dried-up stream that used to flow into the nearby River Ravensbourne.
"This cluster of coins suggests that travellers along the road used to throw their loose change into the stream to bestow their journeys with good luck or, perhaps as an offering to the gods," said archaeologist Geoff Potter.
A Thames Water spokesman said the coins will be cleaned and are expected to be placed on display at the Bromley Museum later this year.