Here are links to the ones I go to the most often. Have fun and eat local!
http://www.hopefarmersmarket.org (East /downtown Austin)
http://www.bartoncreekfarmersmarket.org (Southwest in Barton Creek MAll parking lot. This spot is also great for getting a view of downtown Austin)
http://www.jbgorganic.com (open M-Thurs 8:30-4:30 and Friday 8-12) Johnson's Backyard Garden)
http://TexasFarmersMarket.org (Cedar Park)
http://sfcfarmersmarket.org/#myGallery1-picture(4 locations around town)
Boggy creek also has a wonderful one on Wed. and Saturdays. Please let me know if you have any additional questions.
Member Austin's Elite25
Realtor, CLHMS, CRS