Most of the phones I find are in a thousand pieces.
I did find one a few years ago, and simply dialed "0". An operator picked up, and coordinated getting it back to the owner.
I lost a few phones in St. Louis Missouri. Actually, I think other people got their phones returned, but mine were all just GONE.

I'm sure a couple were found.
I've found phones in stores a couple of times and turned them into customer service, but I always wonder if they just get tossed in a box, and ignored until the box is dumped out at the end of the year.
I found a set of car keys recently with a FOB from a local gym. I took the keys to the gym as they should have had the owner's contact info, but the employee again just wanted to toss it into lost and found.