It depends on a lot of things...
If I find a $100 bill, how would I find the owner?
If I find a wallet, or something else I would be able to tell the owner's information, it would be easy to find them, and I will.
If I find a rare antique, or something that seems like a family heirloom, something that seems like it could be important to someone (and fairly unique), I would do whatever I can to find them.
Why?
What did you find?