Just a lovely little thing. This is a late 19th century cast iron wheel, which I believe most likely was one of two wheels on either side of bell, which would ring and it was pulled along. (Probably made by J&E Stevens.) I'll never say no to a ring of hearts, and would probably mount this one the wall from a nail, though it would make a nice ornament for the tree, too, hung from a ribbon.
3 13/16" diameter. Aging to the iron as evident, stable and sound.