Cercocarpus montanus...which I believe is native in some parts of Texas.  Evergreen, nitrogen fixing...drought tolerant...grows to 12'+...slowwwwly.
 
 For pine species P. edulis (Colorado Piñon), P. sabiniana (Gray Pine), P. cembroides (Mexican Piñon)...several others...
 
 Depending on your rainfall ("central texas" is a tough descriptor to work off of, given the size of the state and huge drop-off in precipitation as you move west), you may be able to do Elaeagnus x ebbingei or Elaeagnus pungens (Silverberry).
 
 I'd bet someone from your bioregion would have a bunch of other ideas too!  
