Love the rugged surface of some of them! I always end up with a lot of quartz...which may or may not be entirely safe, depending on what else is in there. But they look so cool!
When I lived in North Carolina it was in a very rural area and the county was covered in small farms, mostly old tobacco fields. Over many years of being plowed the farmers had dug up a lot of rocks and so there would be large mounds of really nice fieldstone, usually at a corner where several fields met. Nobody would say a word or complain about someone helping themselves to some rocks there. I miss that. Nice rocks, btw. I wish I could find stuff like that here in Texas. There are good areas, just not where I am.
When I was looking for rocks recently I couldn't believe how hard it was to find some that weren't limestone here. I couldn't believe I might have to PAY for rocks! ROCKS!