A Little different take.... Oldest coins I've dug while using my detector.
Penny: 1894
Nickel: 1908
Dime: 1917
Quarter: 1940
Half dollar: 1943S
Dollar coin: 1976
With Canada just across the river Canadian cents circulate along side US cent here. Nickels, dimes and quarters pop up now and then but do not circulate.
If I take a roll of coins to the bank the teller checks them with a magnet for Canadian.
I've read several places that the nickel was used for armor plate for tanks. A little bit of checking seem to bare this out as Nickel steel plate was considered the best at the time.
I believe you have a Thailand y328.1 10 Baht (1996) 50th Anniv. King Rama.
http://worldcoingallery.com/countries/coin.php?image=img5/175-328&desc=Thailand y328.1 10 Baht (1996) 50th Anniv. King Rama