Mud Wallow Game
This Game is meant for Boy Scouts.
kiddie swim pool
small bucket for each patrol
dump the coins in the kiddie pool. Fill the pool with mud.
Make sure there is a lake, river, or hose available to wash off after the event.
Each patrol has a small bucket.
Patrols gather 10-20 yards from the mud hole.
On 'GO' signal, one scout from each patrol runs to the mud hole with his bucket and searches for one coin. He raises the coin over his head and shouts "Eureka!" or some such exclamation and drops it in his bucket.
He then runs back to his patrol and passes the bucket to the next scout.
Continue the relay until a time limit is reached or it appears all coins have been found.
The patrol with the most coins wins.
A judge by the mud hole may be needed to ensure only one coin at a time is recovered.
You could have a Trading Post where patrols could exchange what they collected for snacks or stuff.
Depending on your budget, there's no reason you couldn't use jello, chocolate syrup, or baked beans in the kiddie pool. You could also collect something other than real coins - plastic coins, marbles, plastic soldiers, whatever - with different values for each item.