Near the USDA building is a small garden growing food.  They 
periodically replant it with flora for the season so that most of the 
items in the garden are ripe at any particular time.  When Di Yin and I 
walked by together at the beginning of July--the first time we were there 
together--we saw carrots, beets, corn, bok choy, melons, basil, 
eggplant, rice, fava beans, and potatoes, all growing nicely.  It was 
neat to see the plants for all these, not only the edible product.