In one photo it appears tapered. It looks like a collar that would be hammered onto a wood tool to tighten up the end to keep it from splintering. Just my 2 cents. I have no idea what it is.
I'm leaning towards BosnMate's thought. I found a dozen of these (although they were round) at a 19th century site that manufactured carriages, buggies and wagons. But where they were used on the wagon is a mystery to me.
The ''blob'' ends on those inside ''pins'' is what throws me off. They are not meant to hold much weight, so I was thinking that a piece of punched leather (as in a belt) would have been on each side, on the inside of the ring..?
Since you got me to thinking, could it be part of a wheel spoke on one of those big conestoga wagons? I just looked up some photos and some of the wheels have collars like these and some don't. I doubt two were ever built the same way as each was crafted by whomever had an anvil and forge.