The rail trail out of Mattapoisett runs flat past marsh and cattail toward Fairhaven, and in late summer the air above it smells of hot pine and low tide. Shaun's Lawns works the streets on either side of it, cutting weekly, trimming tight to posts and bed edges, edging drives, mulching, weeding and overseeding as the season allows. Cleanups open the year in April and close it in November, with the leaves cleared off the grass before the first hard rain glues them down. None of it is complicated. It is showing up on the same day every week and leaving a yard better than it stood seven days before.