OCALA: OcalaNF about 50 miles NW of Orlando. A favorite free campground is Hopkins Prairie, a few miles down a bumpy road from Rt. 19 on west side of Lake George. Road is well marked. No hookups, pit toilets & water of questionable quality at center of the camp area. Groceries are available in Salt Springs, 8 miles north of the campground.
Since some of the info Bob has posted has a few years on it here is an update.
Hopkins now charges $10.00, 1/2 with golden age. As of march 2011 the water pump was not working.. If you have a class A motorhome caution is advised as there are low hanging limbs on both loops so good to walk first. I actually measured clearances at 10 ft or less. Campground is heavily used by locals on weekends.
At one time this campground was pretty informal but at some time in the last ten years has been marked of into numbered sites and now has a host.
Further north, just south of Salt Springs is Shanty pond $8.00/4.00 with lots of large wooded sites. Occupancy was light even on weekends, possibly due to a temporary ban on tents/ tent campers due to bears.
Water pump there does work.