It reminds me of a bottle opener from old soda machines... but I could be remembering those wrong.
Edit: yeah, no, that's not it... I must just be thirsty.
Looks like a handle that would be put on the side of a box or crate. Either that or something that you could hook a strap on to in order to lift something or hold it down. Think of a fabric strap with a wide metal j-hook on the end.
Wow benz great detective work. This was found in Rehoboth, MA just a skip away from Providence, RI which is where this jockey plate was patented. I've found a bunch of horse tack at that same location. Very cool! Thank you!!!