Jack Sheehan, 13, of Sandwich, said he found the bag on the street while he was walking his dog on Halloween and he wasn't sure if the money was even real or part of a costume when he turned it over to police, The Boston Globe reported Thursday.
"I felt like it was the right thing to do," Sheehan said. "I'm happy they got the money they lost. A lot of people I know would have been on the fence of what to do."
Police said there were deposit slips in the bag stamped MCS, leading them to the Mashpee Country Store.
Mohammad Rafiq, who owns the store with his brother, Mohammad Ahmad, said Ahmad left the bag on top of his car when he drove off to deposit the cash.
"It fell on the way somewhere," Rafiq said. "We were looking for it here and there."
Rafiq praised Sheehan for returning the cash.
"The kid was really good," Rafiq said. "It is not usual that this kind of thing happens."
Rafiq said he and Ahmad rewarded Sheehan with $100 and some bags of candy.