Our CSA box contains a variety of fresh fruits and vegetables which changes throughout the Summer as the harvest season progresses.  We grow many of our own vegetables and work with a couple of other Thurston County farms to fill in on the vegetables we don't grow or have in rotation throughout the season.  In addition, we direct source seasonal fruit from small family farms throughout Eastern Washington.  An early season box will be a little less diverse and ample than a mid to late-season box.  Here's a very general sketch of what a season of CSA boxes may contain:

Early Summer
Lettuce - 1 or 2 heads, plus two or three other salad items like radishes, turnips, arugula, edible flowers
Spinach or Kale or Swiss Chard
Snap Peas
Broccoli or Cauliflower or Romanesco or Cabbage
Carrots - 1 or 2 bunches
Beets - 1 bunch
Scallions (Green Onions) - 1 Bunch
Mixed Fresh Herbs
Strawberries - 2 to 3 pints

Mid through Late Summer
Lettuce - 1 or 2 heads, plus two or three other salad items like radishes, turnips, arugula, edible flowers
Spinach or Kale or Swiss Chard
Snap Peas or Shell Peas or Green Beans
Summer Squash - 3 to 4 varieties
Cucumber - 1 or 2
Walla Walla Sweet Onion - 1 or 2
Yellow Onions or Shallots or Garlic
Broccoli or Cauliflower or Romanesco or Cabbage
Carrots - 1 or 2 bunches
Beets - 1 bunch
Potatoes - 2 pounds
Mixed Fresh Herbs
4-6 Pounds of Seasonal Fruit including Strawberries, Apricots, Cherries, Peaches, Blueberries, Nectarines, Melons, Plums, Pears and Apples

CSA stands for Community Supported Agriculture.  The idea behind CSA is that the community that eats the produce of the farm helps with the upfront cost of each season's crop by signing up for a "share" of the farm's harvests.  This shared capitalization between the farmer and the community is important to assist the farmer early in the year when there's a lot of money flowing out for seed, soil amendments and other costs related to bringing their crops to harvest later as the season progresses.  The community then gets repaid each week during the CSA season with a share of the farm's production.