Logged in to comment on this:

Turn it in dude..if it was in a Walmart bag or something, it would be different as that would mean it was probably drug money. But it's in a bank bag. It's probably some small business payment or something..I know it's tempting but turn it in. TO THE POLICE, not the bank. The bank would probably just keep it and not try to find out whose it is..give it to the police, notify the local bank (the one on the bag) and wait to see if it's claimed.

Do the right thing man..