My people have always referred to them as Chamaca rocks as do most all of the tribal elders here.Here are a few of my favorites and a couple more I have liked........
I've seen some some nice mortars in situ in AZ, good sized with a slight depression an inch or two deep ground out, but didn't actually consider removing them, a little hard to slip in your pocket. We were Javelina hunting and ran into a small metal "sensitive area" sign, which made us switch to relic mode....found some nice stuff, but left it in place. We wouldn't have seen it if not for the sign.