I'm going to start this as a central place for LA Festivals. There's nothing like the small town festivals where you get some of the best local food, music and scenery. I won't list dates as they sometimes change and will only list the festival name, website (if one) and general timeframe it's held. Visit the festival's website for current information. If anyone knows of one in your area, post it up so this thread can be living and stay updated.
Down here we have the Yambilee Festival and the Zydeco Festival. The Zydeco Festival was earlier this month, so it wont be around again till next year, but I think the Yambilee is coming up. Ill have to check and see.
It has just passed, but early in August, we have the Pennington Hot Air Balloon Championships, which is a free event to the public. Don't know if you would consider that to be a festival, but it is a good time.