Left in plain sight around Blackhall Colliery, bundles of £20 notes usually totaling £2,000 ($2,581) have been found 12 times since 2014.
The latest discovery was made on Monday and police have praised residents who have been handing the money in.
Detective Constable John Forster said that four bundles have been found so far this year, and their provenance remains unknown despite ongoing investigations.
"This could be the work of a Good Samaritan but we would like to thank the residents who have shown incredible community spirit by handing the money in," said Forster in a police statement.
"The circumstances remain a mystery so we would welcome any information that will help us get to the bottom of these random incidents."
Police said the bundles have been found in different locations around Blackhall Colliery.
The force said many people and organizations had been interviewed in the village in a bid to trace the origin of the bundles.
Checks with the local bank and post office had been carried out, as well as testing for fingerprints.
The honesty of village residents has been matched by other people around the world who have sometimes handed in life-changing sums of money they found by chance.
Police later confirmed that a Manhattan woman filed a report about the bag, which she'd lost as she headed off on a vacation to Russia.