Not even the foggiest-headed stoner would argue they want children to smoke pot. (Especially if it means children digging into one's stash.) The challenge is in dissuading kids from doing so without resorting to potentially counterproductive myths and hyperbole. Enter Ricardo Cortes. Last month, Cortes published his children's book, It’s Just a Plant, 48 cannabis-laden pages that he hoped would be taken as a welcome dose of "reality-based education." The former high school D.A.R.E. officer and Brooklyn-based T-shirt and skateboard designer says the book is intended for "six- to 12-year-olds." It still encourages kids to say "No," but stops short...