One of my favourite pictures I have taken of flowers. For the longest time I had never been able to identify this plant, but after an hour of searching the internet, I found it:

Guayacan (Guajacum angustifolium) is the species of this plant.

I did not grow up in Texas, so a lot of flora and fauna are not in my memory banks like most of them in Louisiana are. I used to memorize bugs and plants that were native to Louisiana, when I was a kid (5-14yo), because I wanted to be an entomologist. Heh, I gave that up. ^_^