It's the size of a quarter. It's either copper, or a bronze alloy. The background has a cross-hatch pattern that is mostly gone. I'm guessing WW2. Can anyone with military button/pin knowledge, help out on this one?
Is is flat or domed shaped? If it is flat it's from the WWII period. If it has a domed shape it's from the WWI era. Either way it's real rare and nice find!