Raised bed - Need help!

We had just lovely weather at the beginning of March.  So, I decided to put a ring around our apple tree for pansies.

I felt so good about it.  Looks good, right?

Then I start reading how if you put dirt over roots of a tree, you could kill it.  Awesome.

So, now I'm not quite sure what to do with it.  I'm thinking I may keep the ring, but put pots inside it for flowers.  I don't know...  THOUGHTS?