This observation is of the mustard-yellow lichen, not the greenish-grey one. McKinney Roughs LCRA Park. UPDATE: After a bit of digging around, it looks like the only mustardy-orangy lichen that pops up regularly in observations for this region is Teloschistes. It doesn't looks like a great match, but in the absence of anything better, I'll add that as an extremely provisional ID. UPDATE 2: In light of @ncowey 's observation of what appears to be the same lichen also at McKinney Roughs, I'm feeling a little more confident and am going to narrow it down to T. exilis: https://www.inaturalist.org/observations/4599234