Are you referring to organized rides (one-day)? Or multi-day tours?
If the former, check out www.bicycle-stuff.com as suggested above. There is no shortage of rides in North Texas during the spring and summer.
If the latter, bummer. You missed a great organized small tour across Texas last year. Bikin' Mike Keel from Plano Cycling and Fitness organized a supported tour from the Gulf to Oklahoma. There were about 15 of us on that one. We did 700 miles in 7 days. It was the best vacation of my life, to date.