"They're all gonna either be 80 milligrams or 40 milligrams of THC," the salesman behind the counter explains. THC is the abbreviation of tetrahydrocannabinol, the psychoactive agent in cannabis.

A short time later, John, an engineer, sniffs the musty-sweet smell of one of the numerous varieties. "Awesome," he says, savoring the moment. Back at home, the only option for buying pot is from dealers in shady parts of town. Now, for the first time, he and his wife, a receptionist, are standing in a bright, cheerful establishment not unlike a grocery store with its wooden floor and sales counters. They have no idea where to begin.