Unusual flute, for sure. If found in texas, then it's a ways away from home. Honestly, it doesn't look like anything I have seen found in cave environs, I don't see any mineralization on it that I would expect to see from there. The antler mouthpiece looks awful pristine too. But, sometimes pics fool people.
Here's what I see. The ceramic and paint itself is reminescent of Western Mexico or even further south. If I had to guess, I'd say Colima(?). Honestly, it looks like more of a tourist item though (don't shoot me for my opinion). I've examined a buttload of meso-american ceramics and can tell you some things to look for. Under magnification look for micro fissures, root traces, calcium carbonate or other valid deposits. Even the tourist stuff has the gray "applied" deposits to make things appear much older than they actually are, don't let them fool you (there are a ton of them on the market). They are painted on then brushed off and adhere only in the nooks and crannies, but close scrutiny will show that they are not actually valid deposits (valid deposits are also much more sporadic). Look closely at the slip. As I stated a bit ago, there should be micro fissures that are visible under magnification, even noticable on the highly polished chimu blackware slips.
Sorry, I went to rambling on! Anyways....thanks for sharing, it's a fun looking piece.