Here's some places

Hidden Falls Adventure Park
Marble Falls, Texas
http://www.hiddenfallsadventurepark.com/index.html

Soggy Bottom ATV Park
Bryan, Texas
http://www.soggybottomatvranch.com/

Brazos Valley Off-Road Ranch
B/CS
http://www.brazosvalleyoffroadranch.com/

Katemcy Rocks
Mason, Texas
http://katemcyrocks.com/

Satans Playground
Juno, Texas
http://www.sp-orv.com/index.htm

Barnwell Mountain Recreation Area
Gilmer, Texas
http://www.barnwellmountainra.com/

Tire Trax Offroad Park
Rockdale, Texas
http://www.tiretraxranch.com/home.php

Canyons Offroad Park
Fredericksburg, Texas
http://www.canyonsoffroad.com/

General Sams Offroad Park
Huntsville, Texas
http://www.generalsams.com/index.htm

That's all I've got