Edit 2: This is in the Longview, TX region (and no, I live in a smaller town in this area)
Mescaline/Peyote

, DMT

, RCs, GOOD Molly (hell, even DECENT x tabs)

, GOOD Coke, Ketamine, Heroin, Oxycodone+Stronger Opioids

, LSD

, and probably quite a few more that I can't think of lol...
Pretty much, you can find weed (usually swag, reggie (swag is not the same, I consider that one tier below reggie), or low-mid grade chronic/hydro...good corn is hard to find) or you can find some meth that's been stomped to shit, you can usually get vicodin and xanax as well, but that's all the ones that are usually readily available. Decent drugs are hard to come by. OH YA! I forgot...you can get x tabs that require me to snort 2-3 of them right off the bat to get good effects and that's if they don't make me puke from everything else in them. You can get shitty coke; I've never ventured for it, but I'm positive you can get crack. You might be able to get methadone/suboxone, but the people that use those really don't get recreation out of them. You can get shrooms during season if you know the right people, and I haven't in a while, and hydroponic/tank shrooms might come around once in a blue moon but they're retardedly over-priced. Twice as much as I would pay per gram, and even more than that per 1/8 or 1/4 zip.
edit: and I've never heard of anyone wanting to buy/sell PCP or Ketamine (which I stated earlier), so add PCP to that list. Add GHB as well.