Cedarville State Forest features 20 miles of hiking trails near Waldorf, MD.
Follow Route 50 West to Route 301 South. From Route 301 South travel to Cedarville Road (at the very end of Prince George's County). At traffic light, take a left on Cedarville Road. As a landmark there will be a large white warehouse located on the left hand side. Take Cedarville Road to Bee Oak Road (on you right) which will be the main entrance to the forest.
http://www.tripleblaze.com/trail.php?c=3&i=582