I found one too, and based on the site where I found it, I speculate that it is a harness or bridle part, since the majority of the things that I find, that are not directly 'house-related' are equestrian equipment (ie- horseshoes, harness-rings, Connelly Bros. bridle buttons, spur parts, plow, wagon and buggie parts, etc.) The leather you said was on your rivets (it's not on mine) would support that theory, too. Ironically my 'Crack Proof' doohickey cracked when I tried to straighten it some!
View attachment 1882731