some might not consider this a farmer's market, but it comes close & is very convenient to downtown
Canino's is located at the intersection of 45 and 610 North on Airline
behind the semi-enclosed store there are stalls with many small merchants
this will give you an idea
unfortunately the front market took a big hit after Ike
but business is going strong in the stalls behind & repairs were underway to the front store when I visited last
Canino's is a great place to get nuts as well as fruits & vegetables
arguably the best Mexican bakery in Houston is just across the street, el Bolillo Panaderia
larger versions of these & more from the market can be found here ------>
http://www.pbase.com/artichoke/houston&page=21 along with shooting information
hope this helps