Hunting as kids we found 3 on top of Mountain here 8 miles from my farm..later We flew over them in Stearman cropduster and took couple of photos. We recognize right away because my sister has one in her farm and we walked right over the edges of them and said, Hey! Nobody builds a wall with no stones...”
Some of them are guess wait for it.mountain lakes... Who woulda thunk it
Looking back now I fogger it was part of a comet breaking up coz couples years ago we found mor in a straight line 5 miles away
Could be caldera - A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption.
Unless the geology says positively no vulcanism!
Also, it would be good to get some samples and see if they show impact stress before concluding they were from meteorites.