Sunday afternoon in Cascade Heights: magnolia shade laid across the pavement, the streets wide and unhurried, somebody's yard just finished and cooling. MYKE LAWN SERVICE moves through southwest Atlanta on weekly and biweekly rounds, mowing, edging, trimming close to porch steps and fence posts, then blowing the walks bare. The big shaded lots take patience, since the mower path has to bend around root flares and old shrub lines while the trimmer reaches what the deck cannot. Seasonal cleanups take out the leaf drop and whatever a Georgia thunderstorm knocks down. The reward is a yard that makes the entire street look tended.