Landscaping around tree and roots

I have seen people just put a nice mulch mound around trees, you could do that.

Yes, a dirt covering the roots is an excellent idea, another idea is to build a box or a retaining wall around the exposed root area and backfill with dirt and plant shade plants, such as Hostas. Beautiful.

Or fill in the area with rocks and place plants in pots in the more open areas.

Try making container plantings around the tree

Since nothing will grow, i would do what ever color of rock yo prefer in a design, put a few ornaments in there too. https://www.google.ca/search?q=garden+ornaments&newwindow=1&rlz=1C1KMZB_enCA517CA517&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiF-tqnrOXaAhUJ5IMKHXRhCH8Q_AUICigB&biw=1366&bih=598#imgrc=LWYUXpGxfijXoM:

Surround the tree with landscaping block, fill with dirt, and plant shade tolerant plants (check with a LOCAL nursery for the best ones for your area). The landscape blocks pictured stack easily, have a "hook" on the back so they won't slide forward. Set your first row level, and calculate the size to use whole blocks... move it in or out until it "works", then add the layers on top off setting the joints.... use landscaping fabric to prevent weeds.

Be careful with filling the area over the tree roots soil. You could end up killing the tree (we found this out when we looked into what do under a pine tree we had). That is like planting the tree deeper than it should be. The best bet would be to put some kind of border and fill in with some kind of stones. The stone will allow drainage so it won't smother the roots of the tree. If you would like flowers you can then put some nice flower pots around under the tree on top of the rocks.