I went for a walk to today, and went past a local construction site where the city is re-modeling a municipal park. A metal detector guy had slipped through the construction fence, and was quietly wandering around with his detector, stopping every so often to dig into the exposed earth with a small trowel.
I don't know about you, but I find these guys to be creepy. Their hobby is based on the idea of profiting by digging up stuff that other people have lost. They are mostly looking for jewelry and rare coins. To me, the right thing to do is to turn in lost property, especially if it is valuable. Perhaps you get to keep it if no owner comes forward.