At one hilltop I visited last weekend I found an isolated pile with a standing stone. I know for a fact that this hilltop is the corner of a property - on my topo it is a corner of one small piece of Leominster State Forest.
If I did not know this was a boundary corner, I might have compared this to the piles with standing "manitou" stones we saw last week from Norman Muller. Note the blue tags on the tree behind:
There was even a hint of quartz in the pile - someone added a couple of pieces.
Nice even though not ceremonial: