In and around DC there are many outdoor farmers markets to indulge in during the weekends. My personal favorite is the Dupont Circle Farmers Market. I like buying local and supporting farmers.You might pay a little more than the grocery store but it is all worth it. Besides the obvious that there is fresh produce from vendors around the area, there is decent people watching and plenty of brunch places in the area to choose from.
Here is a list of a couple of my favorite vendors that were at the last market I went to on Sunday 06/09:
Fruitive, Virginia Beach, VA
Urban + Ade, MD
Sunny Side Farm & Orchard, West, VA
Black Rock Orchard, Lineboro, MD
Toigo Orchards, Shippenburg, PA