For East Bay boomers who find themselves unaccountably awake before dawn, you might want to do something besides lie there listlessly. Near Jack London Square the Oakland Produce Mart is in high gear at dawn. Trucks delivering the fruit and vegetable treasures of the San Joaquin jam the streets. It’s a vivid agro-industrial scene around 2nd and Franklin out of old social studies textbooks. Bring your camera. You can’t buy anything so grab a blue collar breakfast at Buttercup Grill which opens at 6.