Saturday morning in New Hyde Park sounds like one mower at a time, and Edwin Lawn Care is often the first of them. The route runs the flat blocks near Clinton G. Martin Park, where the lots are modest, the sun is unobstructed, and the whole difference between cut and cared-for lives in the edges. Grass down, string trimmer along the fence line and around the mailbox post, blower across the walk until the concrete is bare again. By eight the yard is finished and the day belongs to the people who live there. April through November, week after week, that is the arrangement.