I don't know about the round one but the square one looks like these I've found and was told when I posted them that they were host rocks. So I think the square one you have is one of those.
reuellis: I was in a hurry earlier and meant to say also I have a nice collection of these but the two in the pic were handy so I took a pic of them. I think they're cool and when I find them I always bring them back. They are unique and make great additions to rock gardens or borders for herb beds and the like. I'm still not sure about the round one, it looks like it has ridges. How big are they?
no rock, i don't know they aren't. that is why i was asking...
monsterrock: no need to apologize for your opinion, that's why i posted them here!
both from the same creek (which i hunt 90%) of the time. i will take some pictures of other items that are flint (these are river stone) that have similar size and shape grooves for comparison.