A very nice forest service campground; good sites by Madison river, some with electricity at good rates. Great access to Yellowstone.
Good campgrounds, nice host, first-come first serve no reservations so you have to show up to know if you can get a site but fills up slower than spots right in west yellowstone and the National park itself. Just a couple short miles from the city, quick drive in. They have a variety of spots but tent camped. Near a cool river but prepare for mosquitos.
first come first serve, real close to Yellowstone, nice host
we paid $20 for a night for spot #60, it was 7pm when we arrived and he said there was still 3-4 spots available. Don't forget to be responsible for yours and those around you, lock your food up