Just found out that this started off as a UT event to look forward to finals week and has turned into a non-profit event, where if you are new to Austin you learn about it quickly as a thing to do. Check out the website: http://www.eeyores.org/
There is NO parking at the park. However, there is a FREE parking garage with FREE shuttle busses to the picnic.
New to Austin is meeting at the state parking garage "E" and lot 3 on Colorado between 16th and 17th streets. We'll get on the 11:30 shuttle to the park, so be punctual.
Look for the curvy dyed redhead in a dress and sandals, carrying a brown leather backpack.
There are plenty of food and drink vendors, but you can save a few bucks if you pack your own booze and water. Plastic or reusable water bottles only as no bottles, cans, or coolers are allowed.
If you've never been, I highly recommend bringing a camera. Lots of people dress in costumes and body paint (you can too!)