Branch Brook runs low and clear by the end of August, and the lawns along it hold their green a little longer than the ones up on the dry slopes. Elvin Gomez Landscaping mows, trims and edges through that stretch of the year and on into the leaf-fall that follows — refreshing mulch, keeping the bed edges sharp, hauling off the cleanup when the maples finally let go. Cutting a lawn well is mostly patience: the right height, the right week, a straight line held across an uneven yard. Mount Kisco's yards run small and steep and full of corners, which is exactly what makes a finished one worth standing back to look at. Chappaqua, Millwood and Pleasantville sit on the same run.