Looks like a canning jar lid to me. I don't know if folks in the U.S. use them but I used them when I lived in Germany. I still have some around here somewhere!
hello cb i found one of those lids in a turn of the century cistern, i also found a broken queen jar in the hole, mabey it was used with your telephone jar mike
A jar lid for sure. Some are worth a few bucks. Do some research. For example: The Cutting lid pictured here is listed at 45.oo in mint cond. Not sure about the milkglass. The top two are commons. You can skip'em for miles! LOL
Sorry I don't know the value of yours. nice find. Oh yea, Take a picture on a solid surface. Your camera can't tell where to focus.