Laurence Parent is your man. Avid backpacker, superb photographer and world-renown for not only his work in Texas but in neighboring states as well. This is the first Texas hiking/camping book I ever purchased, and the one I use most often (that, and Parent's
Official Guide to Texas State Parks).
Hiking Texas, by Laurence Parent
If you ever head out to Big Bend National Park, which I urge all Texans and travellers to do, also pick up Parent's
Hiking Big Bend National Park -- it's a superb companion guide to the official National Park Service 3-booklet set (which covers the parks paved roadways, 4x4 roads and hiking trails).