Oh wait, that's a different kind of tree ring.
I have a Sweetgum tree that the roots grow along the ground. It had a small, round, concrete ring when we bought house. Always looked like crap (tuned it twice). So time to do something different.
Attachment 10736
Had some old plastic border laying around.
Attachment 10737
Dug it in, added dirt and 4 Mirage Hot Pink Autumn Sage plants.
Attachment 10738
Not 100% satisfied, but much better than before. Think I'll like it more when plants mature