CSA stands for Community Supported Agriculture. Here's how it works:
You pay in advance to buy a "share" of a season's worth of produce from a local farm. Then on a weekly basis you go to a set location (e.g. a church, a community center, a local business) and pickup your produce for the week. I was a member of Norwich Meadows Farm in New York for a number of years and I loved it. I recently signed up for the fall/winter season at Steadfast Farm here in Arizona.
One week you might get 5 pounds of tomatoes, kale and spinach. Another week might be 6 ears of corn and squash. It's farmer's choice depending on what is ready to be harvested. Which means what you're getting is generally fresher and tastier than supermarket produce. The flip side is you don't usually know what you are getting until you show up and you might be forced to improve your culinary game by preparing something new.
Farms that offer CSAs tend to grow more interesting things than you can get in a grocery store - often heirloom varieties. Take the classic heirloom tomato for example. It doesn't have a symmetric shape or uniform coloring but it tastes far better than any supermarket tomato. A true heirloom crop is one whose best seeds have been selected and replanted from the prior year's harvest for 50 seasons. Looks weird, tastes great and is suited to the soil and climate conditions of that region.
By joining a CSA you are voting with your dollars by divesting from large agribusinesses who often are not acting in the best interest of people or the planet. If you value our natural resources and enjoy good food, make an investment in yourself and the planet by joining a local CSA today - they are all over the world.
How to find a CSA near you: http://www.localharvest.org/
If you already are a member - leave the name of the farm below in the comments section.