Serious Eats - seriouseats.com

Check out the Eat Well Guide at www.eatwellguide.org - they have a huge collection of fresh, local food in the Washington D.C. area, and across the rest of the country. If you think eating locally is important, it's a great resource for finding farms, farmers markets, CSAs, and restaurants and stores that focus on selling meals and ingredients from local sources.
Also, if you're heading into Washington D.C. this upcoming week for the inauguration, they just came out with a guide that helps find fresh, local food en route instead of the normal fast food. Hope that helps!