Photo: Arty “Fucking” SmokesLettuce all wear hats: This lady is clearly a veg head. But if you haven’t crunched your cranium over lettuce, there are some shocking facts out there. Like, did you know that switching to organic lettuce cuts down on dietary nitrate, which has been linked to various forms of cancer? Or that 90 percent of leafy lettuce is shipped in from massive farms in California? Beleaf me, you want to spend your green on farmers market greens.