Earlier thread in Eventing on Boarding
Ashburn doesn’t have tons of farms, it is now a sea of houses, but the above thread mentioned many barns.
Here are a few barns I can think of, with which major roads they are off of (so she can view a map).
Cavallo Farms (Kennett Square) is off of Rt. 50, not far from Ashburn, Fox Chase Farms is in Middleburg, a couple of miles east of M’burg on Rt. 50 (Formerly Paperchase), Compass Rose Farms (JGrass is on here) is w/in commuting distance, down off of Rt. 15 South of Rt. 50 , HayMarket there, with Fairview Horse Center (find a post from her to get her website), there are a few small farms in Fairfax County, Angelica Run is in Oakton on Hunter Mill Road, between Rt. 267 (aka Dulles Toll Road) and Rt. 123.
There are several farms on Rt. 15 south of Rt. 50, one is called Sunny Day Farm (I think).
There is a property on the north side of Rt. 50 not far from Cavallo that has 3 boarding barns on the same property, on of which is Greenway riding stables (they have rental horses)…and while I should remember the name of the others, I cannot.
Depending on what she wants, how far she wants to drive she may look at private barns, that board one or two horses.
Maybe some others will add to this, or add corrections if I’ve gotten any names wrong.