The first pic is interesting .... Could you post more pics... Dose the groove run all the way around and does the flat end look broken? It could be a pestle but it almost looks like a grooved hammer stone. I found o e with a round back like yours and than had a nice axe head on the other end.
The round stone looks natural to me. The grooved piece looks like it may have been that start of an Axe that was never finished or it's a Grooved Maul. Can't really say for sure from those pictures. The last piece your grandfather found is most likely a natural Concretion.