the 3 of us hit some cellar holes.Todd had a great day in my opinion. Lynne got a fatty IH 1863.Todd will post I'm sure and I got a sand cast counterfeit KGII. Often we find these larger back portions of buttons (on right side) at cellar holes.I believe they are like the blow hole buttons.I think the gas got trapped in these and resulted in a poor sealing of the 2 pieces.the one on right is the back portion.front is gone.todd dug one same size as one on right complete yesterday at a colonial cellar hole.i dug these 2 pieces later in the day after his.i noticed while cleaning the button on the left that it's a cuff sized version.hollow 2 piece as you can see from side view it's ready to split open.do these pre date the blow holes for this reason?