I hold out hope that it's a 1916. Not that it would have any real monetary value, but would still be cool.
Based on mintages, the odds would be higher to win the powerball than this being a 16d I imagine. Still, it can be a hole filler until you get one.
Based on the shape and position of the "D" and the shape of the feathers on the helmet, it's post 1916. You can safely spend it.
It was hit 15 times with a arrow as it was being used as an arrow target in place of a bullseye. afterwards they must have lost it somewhere in the grass where it was buried for approximately 70 years and then found via metal detector.
Looking at it from the reverse, it's like the top to a beer can. The "tab" is separated from the coin, except at the top. If you grabbed the bottom of it and pulled it up, the hole would be exposed. Looking at it from the obverse, the center is a "hole", and what you see thru it is the backside of the "tab". If you shine a light at it from the obverse, it shines thru along the edges of the "tab". If that makes any sense................
