there is a store in College Park called The Yarn Store, i think. or the Yarn Shoppe, its by Rugged Outwear. in this like strip mall thing. ask someone. grr.. im not as helpfull as i think... ill ask my sister who lives in mount reneir (im in Takoma) tomarrow, how to get there. it might verywell be on the green line.
i dont even know if its still open, but ill try to tell you the street its on.
there is prolly something closer and actually IN dc.
i really hope you like dc. its been kinda humid, though..