As with the narrow-leaved yuccas, these "Spanish-Bayounet"-like yuccas are a little problematic in Terrell County. Of course, flowers and/or fruits would help, but many/most of them had some indication of a short trunk up to 1 to 2 m tall, thus I'm calling these Y. torreyi (Torrey Yucca) rather than Y. baccata which may also occur in the area.

Taxonomic Note: I see that the USDA PLANTS database maintains Y. torreyi as a distinct species while ITIS considers it a synonym of Y. treculeana (of Central and South Texas).
http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=43123
http://plants.usda.gov/core/profile?symbol=YUTO