Flatstick, I have been to the Devil's River State Natural Area, and yes, you NEED to go! There is a small stream that runs through the area, a tributary to the Devil's River (a.k.a. Rio San Pedro before a white guy decided it looked like it should be called the Devil's River, according to the TPWD circular I had on the place), and I forget the name of the creek but if it is flowing, you should check out a big pool just below the last road crossing of this creek before you reach the River itself. I did a backpacking trip there in January of 2005 with a buddy who was training for a hike on the Continental Divide trail later that year or the next. This creek was flowing only because the park ranger I talked to said they had received 2 1/2 times their normal rainfall amount in 2004 (45" as opposed to a normal 18"!), and no fish were evident until the last road crossing, below which was a good 10-foot waterfall and a huge rock-walled pool full of that beautiful blue-green Texas Hill Country water. This pool was FULL of fish, including some great big smallmouth (4-5 lb. range) and some channel cats just as big, as well as largemouth, bluegill, green sunfish, longear sunnies, and spotted sunnies (the last supposedly introduced, as were the smallies of course, but I think everything else was in fact native). I started out with a spinning rod and chartruese Mister-Twister-type jigs (substitute a 5-weight with weighted chartruese Woolly Buggers and I'm sure you'll get the same result) and big fat bass and cats were busting me off on 4-lb. test. I did swtich to a fly rod and caught a few sunnies on a Clouser Minnow. If you go and find this pool full of water, hit it hard and I doubt you'll be disappointed!
The other place I recommend, a bit closer to home for you (where are you located at?), is the San Marcos River. Spring-fed, crystal clear (at least in the headwaters and for a few miles downstream), and LOADED with nice bass, numerous sunfish species (including 10" redbreast and redear), Rio Grande "perch" (actually a species of cichlid some folks keep in aquaria), and some spotted gar (had the fight of my life from a 20-incher once!) - plus LOTS of public access all through the town of San Marcos (though watch your backcast for college kids - it's the home of TX State!). I actually located many of my best fishing spots there by snorkeling.
Another place I never found my way to (the San Marcos kept me busy and was only 5 minutes from my apartment) is the Guadalupe River below Canyon Lake Dam, which is supposed to have a fine tailwater trout fishery, the southernmost in the continental US...
Also: go take a hike in the Enchanted Rock State Natural Area near Fredricksburg, get around the big pink granite hills, and in the back portion of the area is a pond which is stocked but apparently (at least in 2005) NOT FISHED!! I caught my largest bass ever - a 20", 5 1/2 lb. largemouth - in this pond on one of my original Killer Bass Flies. In fact, that's where this fly got it's name!! I also caught dozens of smaller bass up to 17", two good-sized channel cats (one on the KBF and another on a deer-hair "micropopper" pattern I like to tie), and about a hundred bluegills the size of my hand. None of the (numerous) hikers even knew there were fish in this pond, in spite of the fact that you could watch largemouth up to about two feet long swim right past you and hear a fish jump somewhere on the pond about every 30 seconds!
I sincerely hope these recommendations will rejuvinate your heart and soul as a flyfisherman. Forget the muddy holes and rivers and find some of that crystal-clear spring-fed Edwards Aquifer water - there's plenty of nice fish to be had (of many species)!!
Jonathon
No matter how big the one you just caught is, there's always a bigger one out there somewhere...