So today's Forsyth News (Cumming, GA) reports that on January 14 a woman reported finding a gun on the sidewalk as she walked her dog. This was in the Olde Towne Bethelview subdivision (nice place, not a slum or ghetto). The gun was a .25 caliber Beretta. Why don't I ever get to find guns when I go for a walk????? (even though I don't need a .25 mousegun when my KelTec P32 is smaller, lighter, and more powerful).
Be my luck it was stolen and I'd get caught and charged with it. On a side note: you find a gun, do you keep it (might be stolen)or turn it in because it might have been used in a crime (and this evidence could break the case). Guess I'd have to call and turn it in (unless it was a really really nice one.
I'd sure hate to find out that the gun was used in a crime, law enforcement has a few slugs in a bag, and they're just waiting to match them to the weapon. I think I'd turn it in, let it be fired for forensic matches, and have the numbers run. If it's clean, I would think it might be given back to you. I don't think I'd put a "lost and found" ad in the paper, unless it was a high dollar piece.
Some friends and I found a loaded Taurus .38 snubbie while hiking a couple of years ago. It was in an Uncle Mike's type soft holster and seemed to not have been there longer than a day or two. It was on national forest land and we turned it into a State Park office located nearby as instructed by the national forest office. They indicated that they would turn it over to the local SO. The trail is often used to ride horses as well as by hikers and mountainbikers and it probably just fell out of someone's pocket or bag.
Seriously though... Keep people away from it, call the police and have someone with a forensics kit gather it up.