We have a nice open air Saturday market here in Coppell from June to October. The downtown Dallas Farmers Market is also nice.

Fort Worth for years had one out of the old Tandy subway lot - not sure if they still run one down there or not (my mom would know).

There are also a couple of great daily "indoor" type Farmers Markets around - two I like are in Lake Dallas (off 35E by Corinth) and Euless (Glade Road - attached to the store with the AMAZING beer selection... and they also make wonderful sandwiches on weekdays at the deli counter in the attached convenience store)

I have been known to schedule extra time on the last day of a west coast jaunt to visit the market and haul home fresh veggies for dinner that night. I remember once checking my bag from SEA-DFW because I was carrying a bag full of fresh artichokes, asparagus, apples, and flowers.