Spinach is the answer. Spinach grows in a wide range of soils provided they are moist and fertile. Spinach devotees should seed about every ten days for a continuous supply. And keep right on seeding into August, as spinach will tolerate a light September frost. After plants emerge, thin them so they are approximately three inches apart.
Space rows about a foot apart.
Keep garden soil moist, but not water-logged. All spinach will do fine in our climate. Photograph courtesy of Joe Meier.