Petaluma has been the setting of quite a few movies. Some that you may have even heard of: American Graffiti, Peggy Sue Got Married, Cujo, Basic Instinct, Howard the Duck, Flubber, Inventing the Abbotts, and most recently, The Tree of Life with Brad Pitt. Unfortunately, I think the part of The Tree of Life film that takes place in Petaluma had many takes of the tree and zero of Brad since I didn't hear of anyone running into him at McDonald's.
We even helped Ronald Reagan get elected in 1984 with the Morning in America commercial created and narrated by advertising agency legend Hal Riney (that I would eventually go on to work for out of college).
There aren't quite as many chickens and cows as there used to be, but the legacy lives on through our annual "Butter & Eggs Days Festival." This merry event features tasty food, chirpy local bands, an abundance of microbrews (we have three within walking distance of each other), farm animals, and arts & crafts. But the real draw is the 2+ hour parade (or more likely the beer garden where you can pretend you're watching the parade.) It's been said that the festival is attended by an estimated 40,000 people. Given that our population is about 55,000 (not counting the chicken or cows) -- either most everyone was at the festival or in the parade.