A buffalo leather laptop/sidebag thing. It was in the box, halfway into the sewer and I got curious at the bus stop and pulled up a corner. Jackpot!
The tag and receipt were still on there, paid in cash, $320 bucks. Called the store, posted on craigslist and put a flyer out where I found it. After a month, no one had claimed it and it was all mine.
Technically, I found my dog in the car when my mom surprised me with her.
And I once found a fossilized shark tooth about the size of my palm on the beach in Florida when I was a kid.