Could be a weight from a gate? Sometimes they put weights on ropes or chains and it was attached between the gate and fence and it would keep the gate closed.

-rj

I have something that looks like this mounted on the wall near the cellar hatch doors on our 1883 brownstone. It looks like it could have been used to hold the door in the open position. As an alternate, it also resembles some type of bell, but I can't see what would make it ring.

To me it looks like a buggy anchor.

A short rope about 4 feet long is attached by feeding the rope through the hole from the rounded side to the flat side, then a knot is tied in the rope on the flat side to keep the rope from pulling back through. A snap is connected on the opposite end of the rope and it is carried in a buggy.

When they stopped the buggy the snap was attached to the horses bridle and the weight was dropped on the ground to serve as an anchor to hold the horse.

Here in N.E, Ohio many of the Amish still carry those weights in their buggies.

Interesting about the buggy anchor. That would make some sense as it was in somewhat close proximity to the former carriage house (now our garage).