Maybe this will help.

Here is a link that might be useful: trees for Texas

In my opinion the best shield tree in the long run for the south ... if you have the room ... is magnolia grandiflora. They are evergreen, dense, long lived and gorgeous. Not a "junk tree."

However, they litter and do get very large. So don't plant them near your walkways, driveway or near a pool. They do better in natural settings rather than in a lawn.

They grow fast IF watered and not planted in a lawn. Some granular fertilizer will help. I have friends who have two magnolias that are eight years old that are now over 20 feet tall and very thick. The trees were three feet tall when planted.

Magnolias should be allowed to grow natural with their lower limbs growing all the way to the ground. If you are tempted to saw them off to allow people to walk under them, then you have planted them in a bad spot.

Nellie R. Stevens holly can serve the same purpose on a smaller scale. The "Little Gem" magnolia also is a small "shield" tree, but grows slowly.

How big a tree do you want - heighth and width, both short term and at maturity - in other words, how much room can this tree occupy before it will be too big? Do you want an evergreen or a deciduous tree? While it sounds like you want an evergreen, do you want a broad-leaved one or a coniferous one? Do you want one that is fairly tall and narrow, or one that is pretty wide? Do you want one that will flower or have berries? Is the area for this tree in full sun, part sun or mostly shade? Do you want to grow grass, flowers or vegetables under or near this tree? Answers to these questions will help decide what can be recommended to you.

I would agree that without knowing any more, a magnolia sounds good. I have a 'Little Gem' that was planted in poor clay soil, mulched, watered for a year, and otherwise mostly left alone. It has grown from about 2' to about 6', in 6 years. I would imagine in better soil and with better care, it could be a lot taller, but it won't grow as fast as the species. Its maximum height is supposed to be 30', and I would imagine that the width will be about 15-20'.

If you want something altogether smaller, than a holly might well be good. Be aware that you need a male plant in close proximity (less than a quarter mile) to a female to get berries, so if there aren't any in the neighborhood, you'll have to plant both male and female trees. And if you have small children or like to walk barefoot in the yard, holly leaves and the prickles can be very unpleasant.

Conifer:
Eastern Red Cedar is the native evergreen conifer. Under optimum conditions they achieve about 2' year. These trees will easily succeed with miniimum care and good drainage. They look good both when young and older.
Loblolly pine is fairly adaptable and fast growing, but your soil should be close to neutral PH or slightly acidic.
Don't consider them the best choice for screening.

Deciduous : Shumard red oak or chinkapin oak should do well in your area. They are about the fastest oaks.
If your emphasis is fast-growing, catalpa is one you might consider. It has a unique look, is a better tree than mulberry or most other junk trees. Will litter ground with bean pods.