To me, the dark center looks like a hole. So maybe these are some kind of mini-geodes? But so many of them, all in the same size range?
Someone mentioned that they look reminiscent of river rocks. I disagree. I've seen plenty of river rocks (lived near several gravel pits, did a fair amount of fishing). I've seen river rocks that were tumbled to a smooth, rounded, almost polished surface, but very few were what would pass for near-perfect roundness. They were in a variety of shapes and sizes. These things, on the other hand, look like someone dumped a bag of dried peas on the ground. Some of the broken ones even look like splitpeas.
The other thing that intrigues me is that "peach line" that so many of them seem to have. Why is it there? I can't see the "river rock theory" explaining that line. For that matter, I don't know why peaches (and plums, and other pit-fruit) have 'em either.
Someone (somewhere in the thread, or was it another thread? Dang fatigue..) mentioned something about a press conference Monday, where they were going to discuss this stuff. Is that something they announced they'll be covering? I'd be real interested in what they've got to say. I gotta think they've been just as intrigued by these things as we have. I hope they don't ignore them.