I don't know of too many dressage barns in that area that just offer boarding. A lot of the trainer-owned barns require you to have the horse in training, or at least purchase a minimum number of lessons per month.
You can find some referrals for trainers on this thread: http://www.chronofhorse.com/forum/sh...d.php?t=126517
I would also recommend that you join the Northern VA Chapter of the VA Dressage Association - www.vadanova.org
The web site has some classified ads, and there are ads for trainers in their newsletter (also on the site).
You can also look at sites like www.virginiaequestrian.com , it has a lot of facilities listed in its Green Pages.
Personally, I've worked with Alison Head for nearly 20 years, so she's my top recommendation if you want a good facility with exceptional care at a reasonable price, plus a trainer who has made multiple FEI horses herself. Alison is in Hamilton, near Purcellville. One of her students, Carolyn Jackson, has a farm near Berryville, just over the WV line.
Amateur rider, professional braider.
Save a life, adopt a pet.
As a previous poster said, most require some form of a training package or agreement, if you are interested in an arrangement like that try Performance Sporthorses at Hunt Club Farms, Berryville www.performancesporthorsesllc.com, pm me for more info if you are interested.