Come September the fairground fields off Route 202 fill with tents and animals and the smell of trodden grass, and for a week Yorktown Heights remembers it was farm country. Jim's Lawn Designs Inc works the lawns that sit between that past and the present — mowing them level, edging clean against the pavement, trimming tight so the shape of the yard is unmistakable. The season opens with a spring cleanup that clears the beds and lifts the matted grass, and it closes with the leaves taken off before the frost sets them. Yards here run from wide-open sun to deep tree shade, sometimes on the same property, and each stretch gets cut for what it needs. Ordinary work, done attentively, is what makes a place look good all summer.