Historically Javelinas where up in north Texas! There have recently been more and more sightings of them moving north which is great!

Here is a range map showing past, present and introduced areas of javelina in Texas! (provided by TPWD)

Is there a javelina tag?

No

They have a musk gland on their back right above tail that needs to be removed first IIRC.

That gland comes off with the skin, I strongly recommend NOT trying to remove the gland separately. Just like "stinky" boar hogs, as long as you don't touch the meat with anything that touched the outside and keep the meat clean - cooked right they are delicious. IMO 80-90% of how that meat's going to turn out is how they are cleaned and prepared (this includes removing the glands on older males), the rest is diet. It only takes a little bit of funk on the meat, it's pretty easy to keep the meat clean. Just talking about smell here, not what gender/age is tender or tuff.