A restored ballpark still stands in Hamtramck, its outfield mowed in stripes that anyone who loves grass can appreciate — and a few blocks away, Hattrick Lawncare Services is doing the same arithmetic on ordinary yards. Late summer is the busy hour: mow, trim the fence line, edge the walk, put the clippings back into the lawn where they belong. The yards are small and the driveways narrow, so the difference a straight edge makes is out of all proportion to the square footage. On an August evening, with the light going amber over the rooftops, a freshly cut block simply looks like a good day. Lawn care in Hamtramck, one yard and one clean line at a time.