I bought a good used tractor this year that came with a disk. I am wanting to plant my first food plots.
What are the best crops for deer?
When is the best time to do it?

Cow peas, clover, sunflowers... And now before the rain stops! lol

Where are you making the food plot in East Texas? and have you done a soil sample yet?

Your best bet IMO from a cash flow standpoint, would be to wait until Sept. and plant an oat/ wheat mix with maybe some peas as Navasot mentioned.. This should be ample time to prep the plot, get soil samples (mentioned by TXhunter) for fertilizer and a better chance of success (due to weather). Of course if your in prime bottom land that hasnt been effected by drought, a summer plot may make sense and it that case, you better get at it!

What rain, go to east texas seed in Tyler and talk to Richie.

Ought to be sand around Etoile. Avoid brassicas in the Fall, they won't turn out so hot unless you happen to be on a clay hill. As green and thick with weeds and wildflowers (prettier weeds) it is likely you won't be able to compete with them right now. I'd disc the plots to hold more of this rain and spray weed killer on them so they don't suck out all the moisture.

disc around area that want to put food plot, have controlled burning, disc again prepare plot & plant. best wishes