Nickels are 75% copper, 25% nickel. I feel this is a metal detector find. Slowing in circulation the high points will turn gray, just like it is doing now. If it were struck on a cent, then would have been struck on a Zincoln, not a copper planchet. On a struck through a cent, the devices would hang over the edge of the coin:


Your coins weight and diameter looks normal. Just an outdoor find.