WHEN Cecilia Foti, a seventh grader at the Bancroft Middle School here, was asked to write a “persuasive” essay for her English class in the spring semester, she did not choose a topic deeply in tune with her peers — the pros and cons of school uniforms, say, or the district’s retro policy on chewing gum and cellphones. Instead, she addressed the neighborhood’s latest controversy: her family’s front yard. “The American lawn needs to be eradicated from our society and fast!” she wrote, explaining that her family had replaced its own with a fruit and vegetable garden.