I lost my wallet once on south street after a long night of partying and 1 week later I got a package in the mail with no return addy and a note saying "I think this is yours".
There was $30 in there at the time I lost it (i think) and when I got it back there was $25 so I'm assuming he took $5 out to ship it to me priority.
Blew my mind...$1000 though? If there was no id in it then I'd keep it.