No, not stupid. Naive.
Were I to find money in that town I’d put up a flyer or something and wait for a believeable person to call me with the right amount. After a few days it would be mine unless properly claimed.
I sure would not involve the police.
I can’t believe it took 40 posts on FR before somebody got it right versus the general sense here that it be turned in. What sense does it make to risk turning it over, rather than report it, if the finder already knows he/she will have the integrity to do the right thing? In relinquishing control, they are further risking the rightful owner’s property.
Hopefully a young 15 year old just became a bit more conservative.