I don't know either, pretty crude looking. What would it have been riveted to, cloth, leather, iron that rusted away? Maybe someone made it during the Chickasaw wars? Or something less cool like a forge bellows Anyway nice find and go back!
Looks like the metal was folded, or bunched as it was called, to form a rounded shape. Maybe the rim for a feed bag or bucket? PS: Maybe type of armor.