The olive caddisflies are hatching in large numbers on many of our trout streams and the trout are feeding heavily upon them. I have my greatest success by fishing my Mr. Rapidan Delta Wing Caddis Dry size 14 upstream in the evenings by fanning my casts over the whole pool. A Light Cahill Dry size 14 and a Murray's Little Yellow Stonefly Dry size 16, and Mr. Rapidan Dry size 14 are three other flies I would recommend having in your fly box to match the hatches occurring on the streams. Fish these on a Classic 7.5ft 5X Leader.
You will have better water levels by coming into the streams from the Skyline Drive or upper reaches of the Shenandoah National Park. If you need help on finding access, see my book Trout Fishing in the Shenandoah National Park.
Some areas of the George Washington National Forest west of Edinburg received some heavy rains last night so I would recommend waiting until the weekend before trying to fish the native brook trout streams west of Edinburg.