Summer's the least interesting time for Farmer's Markets in Phoenix, but there are a few that are year-round. Check out the Town & Country Market on Wednesday afternoon and Road Runner Park (on Cactus) on Saturday morning. The Phoenix downtown market on Saturday morning has fewer producers during the summer, but check out Maya's Farm for local eggs, herbs, flowers and some produce. The larger market in Mesa is the one on Center Street on Fridays, but I'm not sure how much they have in the heat of the summer either. Another summer option is to visit some of the farm stands in the West Valley such as Tolmachoff Farms. The best way to get fresh local produce in the Phoenix area is to join a CSA, although again they tend to run from October to July. Try Desert Roots Farm or the Little Farm in Gilbert. Victory Farms was serving central Phoenix, but this is their last week and the future is uncertain.