The whole nutting stone never made sense to me, first of all prehistoric man would have ate primarily chestnuts, and you don't need a depression to place them in, just a flat rock.
there was a very interesting article in the Ohio Archeologist a few years ago, by a flint knapper that figured out their probable use.
He said when knapping flint with a deer antler, the flint tears it up quickly, so you have to keep dressing the antler as you knap.
Sandstone works well for this, and after a while, the depression is too deep for the antler to fit in, so you start another hole.
this makes perfect sense to me, because I have found some chunky cup stones, with cups on all sides.
I never though if you had a basket of nuts to process, that you would pick them out one by one, place them in cups, and then crack them. It seems to me that you would grab a hand full, lay them out on a flat rock, crack them, and pick out the meat.
Old beliefs die hard, I have presented this to a couple old artifact collectors, and they scoffed. Wouldn't entertain it for a second.
In my opinion it makes perfect sense.
Mickey, the 4 stones you show look like hammer stones to me, I'll bet the edges show a lot of wear. The little depressions on the sides, were to offer a grip for fingers, as cracking bones for the marrow gets very greasy.