Patuxent River Park, Prince George County, Maryland
The roads in Patuxent River Park aren't bad from what I've found so far. They are incomplete towards the southeast side of the park, however, and I'll be adding that information in the future.
Today I made a few minor modifications to the existing roads.
None of the trails are in OSM. I've started mapping them but there are several miles left to go. If the weather continues to hold out perhaps I'll have them done in the next few weeks/months.