Upper Chattahoochee River Campground
This campground is a first come, first camp campground, no reservations. I love the seclusion of it, tucked deep in the Chattahoochee. There are a few campsites along the water. Facilities consist of a hand pump/flush toilet and water well, no showers. You can also find hiking trails, including a short hike to a beautiful waterfall. The campground will fill up on holidays and summer weekends. If you manage to get up there early enough, there are several free campsites along the gravel road going down to the official campground. These sites are a gem for people who love secluded camping. You'll have to pack everything in though, including your drinking water.
Don't expect any cell service once you pass Helen and head up the mountain.