It's not like you're the only one that's done that. I had a bag of items I purchased. I usually use those plastic bags as garbage bags for my car.
Only I had an envelope of money from the bank machine. Something like a hundred bucks that I carelessly threw in the garbage bag too and threw it in the trash.
It wasn't until I got in a store and needed it to buy something did I realize what happened and went back to the trash can to get it.
I was lucky to get my bag with the money back.