Greenbelt Campground

This is a very reasonably priced campground for the area at $20 per night. The sites are small and not terribly level, but the back-in sites work well for tents or small RVs, while there are certain sites that work better for larger RVs. There's a dump station and water available, but no electric or water hookups in the sites themselves. Each camping loop has restroom facilities and hot showers.

There are several small trail loops here, as well as a ~5 mile perimeter trail. There are a couple of nice day-use picnic areas. You will definitely spot deer in the drive into the park, so take it slow. The big draw is, of course, the park's proximity to DC. Don't expect to see stars here, but it is surprisingly quiet at night. And it's a great jumping-off point for trips into the Capitol.

This camp ground is also one of the few in the region that does not close for the Winter.

Really great place for a cheap stay outside of DC with tons of beautiful nature and really nice campgrounds. All the campgrounds come with a fire pit and a picnic table. Very close to the city ~15 minute Lyft. A lot of really nice trails that are maintained well if you need an escape from downtown as well