I've got a maple in my front yard (think it's a Norway) and at the base I noticed some mossy weeds growing instead of grass. The surrounding area beyond that has quite a lot of clovers, mostly on my neighbour's side of the yard.

Can someone tell me 1) what are these, and 2) should I be concerned about them, for example are they a sign of any issues. I'm not worried about it, just interested in any perspectives here.