Here's our growing
wildtexas.com list of Texas backpacking & hiking clubs. You will find some in there based in the DFW area. One that I know of is thee Sierra Club -- they do a lot of outings, and you don't have to be a tree hugger to participate (though most hikers & backpackers know the merits of trees/nature, even if they don't advertise themselves as "tree huggers" or environmentalists. Hard to enjoy nature and
not want to see it protected and managed properly.