Let's make this the "official" listing of the off road parks in Texas. List the park name, nearest town, a website if they have one, and if you have any experience there. Post the info you have and I'll update this post so as to keep all the info at the top.
State OHV Parks Link - The parks that are working with the state like Bridgeport and Barnwell
Canyon's Off Road Park - Fredericksburg
Cline Ranch - Lake Hills
Consafo Ranch - Kerrville Limited openings
Hidden Falls - Marble Falls, TX
K2 (The new Katemcy Rocks) - Mason
Long Ranch - Llano
Trees Ranch Offroad - South of I-10 between Kerville and Junction Open very limited weekends during the year; but the off roading is supposed to be amazing.
Bridgeport OHV Bridgeport Park has trails for all kinds of 4x4s; not very 2x4 friendly now.Pictures 1 Pictures 2
Brushy Creek Motor Farm - Royse City
Off Road Motorsports - Itasca Purely a mud pit for mudding.
Rock Trails of Tolar - Tolar The park is coming along nicely; check their Facebook page for a guide to get the most out of the park. Pictures 1 Pictures 2
Whitehead's Red River Mudbog - Garland Plenty of mud even during a dry season. But bring somebody with truck that can pull cause most people out there tend to not lend a hand. *reported by user*
Barnwell Mountain - Gilmer, TX Pictures 1 Pictures 2
Brazos Valley Off-Road Ranch - Bryan, TX open by reservation only Pictures 1
Shiloh Ridge - Alto
Down South Off-Road - Crosby (15 mins NE of Houston) Pictures 1
General Sam's Off-Road - Huntsville
Creekside Offroad - Splendora, Tx Reported to have lots of mud and tight trails; no rocks reported.
Satan's Playground - Juno
Texana Off Road Park - Blackwell (between Sweetwater and San Angelo)
General Land Office land west of Big Bend National Park - South of Marfa ( Lat: 30°18'9.83"N , Lon:104° 1'49.49"W) and head to the border on RR 2810
Not in Texas - but close:
Buzzard Canyon Off Road Park - Sayre, Ok Look for info on Facebook page
Disney - Langley, OK
Green Acres - Clayton, OK <<no website found>>
Superlift ORV Park - Hot Springs, OK
OHV Parks that have closed:
Rock Creek Off Road Park - Lipan
Spring Creek Off Road Park - Spring