Good listing of various types of Public campgrounds. since skoolies are welcome in public campground... enjoy!
You can download a list of POI for your GPS in Excel. Since I do not have a GPS and I do not care for Excel. I cut and pasted the listings into an Openoffice spread sheet With each state's listing on it's own page. this allows me to sort by town then name. Makes it a little easier for me since I use maps not software to plan our trips by.
http://www.wxtoad.com/uscampgrounds/