On our annual climb of Mt. Adams there was a snow embankment covering the roadway up. By our arrival time the night before there were no camping spots left at the highest point accessible by the road. Morrison creek campground was a great little spot for us to find ourselves in. There is an outhouse available, though you might want to bring your own toilet paper just to be sure.
There are fire pits available, and many sites that can be used to pitch a tent or park. I chose a tent, my friend slept in his car. In the morning we were able to find a parking spot about a two mile hike away from the trailhead. There is Morrison Creek running through with plenty of fresh glacial run off water that can be filtered. Glacial melt is the BEST tasting water in my opinion. If you have never filtered any I recommend you do for the crisp experience alone. There are small single tent sites. There are also larger sites that would be suitable for larger groups. There was a sizeable group of starwatchers that appeared to be able to camp together. It is small, however, there is a covered area big enough to accommodate a medium group tentless. Otherwise you could fit a couple one person tents or a multi person tent. Great spot. I am glad we found a site as we arrived close to 10 pm.