We think this is a trivet? Or a part of an antique cast iron stove which was once used in part as a trivet?
This measures 7 1/2" in diameter overall, and is 6 3/4" over the center flat portion from the inside. It's entirely made of heavy cast iron with a hole for hanging. The reverse is marked ROY SC (we think? we are certain about the Roy part, much less certain about the following letters).
The white paint is clearly old, but also clearly not original. It's a great looking old piece, and does make a good trivet, and would look nice on the wall, as well! Please email us if you know anything about this piece, we've spent a long time trying to figure this one out, and would like to get to the bottom of this msystery once and for all!