Sacramento Area Mustang Club is sponsoring a Ford show in Sacramento, August 4. I'm not aware of a swap meet being scheduled however. You can check out their web site, www.SacramentoAreaMustang.org, for more info.
We're http://bama.4mg.com/ having our 2nd Annual Ponies & Snakes show on Aug. 11 in Danville but there is no swap meet. You might try coming out and asking around.
GoodGuys is having a car show in Pleasanton in Aug. sometime and they have a swapmeet at their other shows (this one is pre '53 cars and sometimes they don't include a swapmeet).