Ask Mr. Smarty Plants

I'm not sure where you live in Houston.  If on the east side of town, you are in the Piney woods. On the south side, you are on the coastal prairie, and if you are on the northwest side of town, you are in the post oak savannah. These are all different soil types with different pH and which hold water differently.  So I'll look at these various places in Texas for recommended trees.  I'll also look at the list of trees for Houston put out by the Houston Chapter of the Texas Native Plant Society. You can view it in the Just for Texans section on the Recommended Plants page.

You'll need a tree that is not too big and which will grow in full sun. 

Acer leucoderme (Chalk maple) would be a good choice for a small tree with beautiful fall foliage. Various sources describe it as a tree that will grow from shade to part shade to full sun.  The downside is that it will need a little more water in full sun and will not be as drought tolerant as it would in part shade. And I think you may have trouble finding it.

Cordia boissieri (Mexican olive) is one of my favorite trees. It is more native to south Texas so is a little out of its range here.  It is very drought tolerant as it comes from an area with much less rainfall. But it will give you a long time of white blooms. You may have to add decomposed gravel to your soil and plant it in a raised bed.  You can set the root ball just a few inches into the ground and then build a  mound of soil over and around it. 

Ilex decidua (Possumhaw) is another one of my favorites.  It does very well in the Texas Hill Country so will be a drought tolerant plant in Houston. And the winter berries are stunning. It puts on the most berries in the full sun situation that you have. And the birds usually don't eat the berries until they fall off near the end of winter.

Viburnum rufidulum (Rusty blackhaw viburnum) is another wonderful little tree.  It will give you wonderful white flowers in the spring, followed by dark blue berries. Then, if fall, the foliage turns  pink to mauve to dark purple. This virburnum grows in drier conditions than most of the viburnums.  It is the only species of  viburnums  that grow well in the Texas Hill Country, so should be very drought tolerant here in Houston.  I have a friend that had a beautiful tree in League City. The only downside I know about this shrub/tree is that it suckers from the roots.  You have to keep it pruned back.

I would keep the root zone covered with mulch. Be sure to start your mulch about six inches from the trunk of the tree and extend it to the drip line. This area will get larger each year.  Then you might want to build a path so only a small part of the soil over the tree roots gets compacted. For very light foot traffic, this should not be necessary as the mulch helps prevent compaction and attracts worms that keep the soil aerated.