On that point about letting people keep small bits, in my experience, that's the only way to avoid hard feelings. Like if you find a jar of old marbles, let them pick a couple to show their kids. For coins, maybe they keep a few as a cool story. But you have to agree on what "small bits" means before you start, or someone always wants more. I once let a guy keep a silver spoon from a haul, and he helped me for free the next time. Your mileage may vary, but a little give and take keeps neighbors from turning into enemies.
My friend uncovered some old jewelry in a relative's yard last year. He used @craig.brian's method and let them keep a couple pieces, which avoided any fuss. That kind of fairness just stops arguments before they start.