Community Supported Agriculture (CSA)?
I think Richard was referring to something akin to a CSA. CSAs sell shares to members who, in return, get a bunch of food every week from the farm. I've never heard of one that allows members to pick and choose ... they are more along the lines of members getting a box of whatever was harvested that week. Either the members go to the farm or go to a central drop-off point. The advantage to the farmer is that it guarantees a market for the farm's output and allows planning at the start of the planting season based on the number of shares sold (East Lansing has a CSA run by Michigan State students that regularly sells all of the available shares). The possible disadvantage to the shareholders is that some weeks they will be stuck with a mountain of, say, chard, forcing them to do some quick planning to use up whatever it is arrived in their weekly delivery.
Another alternative is a food co-op if there is one in your area that makes a concerted effort to support local farmers. The East Lansing Food Co-op is just such an organization. Much of the produce is labelled with the name of the farmer or farm that produced it. Some co-ops (and maybe some other stores too) have joined in a promotion called the 100-mile diet. Everything in the store that is produced within 100 miles of the store is labeled, enabling shoppers to maximize their purchase of locally produced items (much more than just produce) as opposed to stuff that's shipped from hundreds or thousands of miles away.