No, I haven't seen them.Ok, so I'm borderline fascinated that the thing exists since I have never seen one. Are those tile slabs all over S.F.?
What is their function?
In this situation, their function is just aesthetic I would say. It's just so that you don't have a patch of 100% grass or other covering. The tiles break the full-looking covering and, I guess, gives people a stable (non-slippery) surface to step on.