Haha, I would say the same thing if one of my hunting buds found one!
I soak them in olive oil and clean with a toothbrush and sometimes use a rock tumbler. I threw a nasty red shield nickel in earlier this week and it actually brought a readable date out of it, so who knows.
Excal 1000, Excal II, Sovereign GT, CZ-20, Tiger Shark, Tejon, GTI 1500, Surfmaster Pulse, CZ6a, DFX, AT PRO, Fisher 1235, Surf PI Pro, 1280-X, many more because I enjoy learning them. New Garrett Ca
If the coins aren't key dates, vinigar and salt works well sometimes. Magic Tumble Clean also does a good job. Mainly I just take them to Coin Star at a super mart. It saves rolling all those things.