Down along the West Branch of the DuPage, the willows lean over the water and go silver when the wind turns them — that is the color Black Willow Lawn Care carries in mind all summer. Naperville lawns run thick in June, fed by black prairie soil and by thunderstorms that stack up in the west and arrive around supper. The work is mowing on a steady week, trimming close against fences and foundations, and edging a line along the walk crisp enough to read from the street. Clippings go where they belong, and the stripes fall the way the yard wants them. By evening the grass smells green and the river light lies long across it.