The woodcocks are displaying at Piscataway Park/Hard Bargain Farm.

My daughter and I saw (we actually got to _see_ one on the ground with 
binocs!) them start displaying at 6:15pm in the fields around the old 
tobacco barn. I'd suggest parking at the first entrance of the park (not 
the one by the boardwalk) just in case the NPS locks the gate on you. 
Cross the boardwalk and head inland from the riverfront until you come 
to the barn and other buildings. We also had three flyover wood ducks 
and a pair of barred owls in the distance. Not a bad way to spend 30 
minutes with your kid.

Good birding all,
Chris Ordiway @ Hard Bargain Farm
Accokeek, MD