Pioneering marijuana cultivators in the hills of Mendocino and Humboldt counties are being pushed to the margins by the legalization they long espoused.LAYTONVILLE, CALIF. — In the mountains of Mendocino County, a middle-aged couple stroll into the cool morning air to plant the year's crop. Andrew grabs a shovel and begins to dig up rich black garden beds while Anna waters the seedlings, beginning a hallowed annual ritual here in marijuana's Emerald Triangle.