I think the pin part is too small for a hitch pin, in relation to the ring. Looks similar in appearance to half a horse bit too but it is very big for that. Could be a tie down or pull ring for any number of things.
Wow that is amazing! So weird that would be there? in a park.. maybe there was a barn or somthen there? kinda makes me want to go back to that park thx for all the help