FM -
it's not quite so dire. you do need to keep in mind your location - Texas tends to the strong sun, hot and dry side. the 'dry' you can overcome with a garden hose. the 'too much of a good thing' sun is trickier for some crops.
so one theory is: start early and beat the heat - you can basically retreat in July . . . come Sept you can usually get a second crop as your frost free season is also longer.
easy stuff to grow
peas - start 'em early - they won't take heat but you can get a nice batch before that happens
beans - green, wax, limas (a fresh lima is a whole different bean . . .)
leaf lettuces & green onions/scallions - get them going early because they won't take the heat
zucchini - one, two plants - they are prolific
cucumbers are easy - but don't like getting dried out - they get stunted and the fruits get bitter
tomatoes
peppers of every sort
sweet corn - but be aware it takes up a lot of space vs yield - plant in blocks, not rows
my best tip for hot areas is mulch mulch mulch. use grass clippings, no grass? - use straw - 4-6 inches deep. helps enormously with keeping an even soil moisture and not cooking the plant roots. I often buy straw bales, run it through my "leaf shredder" to make it a bit finer.
some not so good choices for the beginner in Texas:
leaf crops - spinach, kale, etc don't do heat well - they'll bolt.
same for "head lettuces"
the crucifer family: broccoli, cauliflower, et al, need a longer growing time and don't tolerate heat - prone to cabbage worms
potatoes - don't take heat well - need to go in early in your area
brussel sprouts - prone to aphids - they can take out your whole crop