I don't have experience with a Microgreen business, though I have started a business in Texas.
If you want to
sell to businesses as opposed to selling at a farmers market there might be some regulations.
You might try starting with your
local City or County Government to see if a business permits or license is require. This can be done
online.
Before starting to do business you would need to contact the Texas Comptroller's office for a Tax Id Number. This will be required for Tax purposes and probably by businesses that you want to do business with.