How could I decorate or landscape around the tree without harming it?

The garden bench idea sounds great, and you aren't supposed to increase the soil height around a tree this can kill the tree.

Around the tree is going to be dry and full of roots and will not make a good garden bed. The easy answer is to dig amongst the roots gently and enrich the soil with aged manures to restore the fertility. Then plant with a tough spreading ground cover. Depending on you climate, pick something tough such as violets, ajuga, hellebores and acanthus mollis don't spread but grow big enough to spread over the roots. All these are growing well under trees for me. Eventually you will have a 'skirt' of plants that need little maintenance and cover your problem.

Do NOT pack dirt or mulch around the roots. You could put potted plants in among the tree roots, but don't mess with the environment any more than that. Those roots need to be exposed exactly as they are. Packing dirt around them won't kill the tree next week, but within a very few years the tree will be dead.

I agree with the first answerer's opinion that a pretty 8-sided bench would be lovely.

In addition to Jeff L. 8-sided bench/seat you could add a 8-sided deck that extends out far enough to hide the roots. (Be careful adding dirt on top of the roots as you can kill the tree.)

They make cement blocks that you set on top of the ground for holding up the underside of your deck. Make the deck just one step up so it can be entered from any direction.

I had the same problem one time and what I did is I went and purchased a truck load of top soil. I spread the topsoil thick around the ares i wanted to cover up. Then I made different flower beds with many different flowers and stepping stones, maybe even some statues. You put enough top soil down that it covers the roots but is still enough for plants to grow. HOPE THIS HELPS< IT DID FOR ME.

you could build an 8-sided bench/seat around it. it will hide the roots and make a nice place to sit under the tree. i saw it done on one of them home do it shows, it looked really nice.

You could take some mulch or dirt and pack it carefully and fairly high around the tree in a cone like way. You could add some flowers to plant in it or bush floweres to cover the dirt so it doesnt look bad.

It's definitely possible, that's for sure

Interesting, I was wondering the same thing myself