Florida is seriously lacking in good music festivals, but there are a few. Check out the Bear Creek Festival [url]http://www.bearcreekmusicfestival.com [url] at the Suwannee Music Park in Live Oak, Florida. They have several festivals a year at this site...Wannee Festival is actually this weekend (June 5-6) and is organised by the Allman Brothers. Looks like a pretty good line up as well. I think that there is also another festival in the spring (I think its called spring fest) which is typically more bluegrass.
And up untill this past year, south florida had Langarado which was gaining some momentum untill they tried to move it to downtown Miami and offered no camping!!!
Hope this helps...