Yep the person who found it, is better off to keep the mouth zipped. I hope Uncle Sam doesn’t threaten the person to indulge where he found it. I am surprised to find that people are still using detectors to find “treasures”. I thought it is illegal since with all government grabland growing.
I find small nuggets on public land all the time. The secret is to look where gold has been found already. If it is rich enough you can still file a mining claim.