TPWD – Texas Parks and Wildlife Department offers an annual parks pass for $70. We bought one our first year here and it easily paid for itself. We bought one this year also and have already benefited from the discounts.
The web link describing all the benefits is here. Personally we have benefited from free entry to parks and significant discounts to merchandise and camping fees.
Last year we visited the Battleship Texas with my sister and brother-in-law. Without the pass the cost would have been about $50. With the pass we all got in free. By the way, that is a neat visit – recommended.
Recently we spent the weekend at Goose Island State Park near Rockport – Fulton. Without the pass the cost would have been over $25 including firewood. With the pass it was less than $12 (for a water only site).
So, if you intend to visit Texas state parks more than a couple of times a year I highly recommend getting the pass. There are several other passes available as well for seniors, groups, etc. See here for more information.