Stop #2 of the Metro Yarn Crawl was Wool Winders in Rockville, MD (www.woolwinders.com), which is a brisk walk from the Shady Grove Metro Station. (I didn't walk. I took a cab, and by some miracle otherwise known as my mother's park-ma (like karma, but with parking), the driver was able to park right in front of the store!).
I got some cute peacock colored stitch markers here.