As a life-long Indian artifact hunter/collector and someone who minored in Archeology ( and worked a few years at a Mississippian Mound complex museum as well), I'd say those are almost definitely indian artifacts. As the others have said, metates or grinding stones. I can't explain the cuts/grooves/pock marks, however, never have seen that before. Whatever the reason, those gashes appear to be done by man. Could be they were trying to shape the bowl area or make "catches" for whatever they were grinding. Most of the metates I've seen are worn smooth from the grinding process. Who knows how long it took for the bowl areas of those stones to get the size/depth that they are but it was probably more than one lifetime. And they're older than Shawnee, as some of the others have said. They could be anywhere from 800 years old to a few thousand, possibly several thousand. Only way to really gauge age on them is if you knew exactly where they came from and could date the site from other artifacts found there. Great pieces in any case but if the show you saw which reminded you of them was American Digger, they're not worth anywhere near what they "supposedly" sold theirs for. Could be worth a few hundred each, or more depending on how they clean up and if you can find the right buyer. Pieces like those are getting hard to find these days, unless they're from private collections ....or someone's flower garden....lol. Actually I think my parents have a metate/mano set that my father found when he was younger and....it's in their flower garden! HH and thanks for showing them. Brad in Missouri