Late May in Barnum, and the evening light comes in low and gold off the west, so every green thing looks greener than it did at noon. DREAM YARD LANDSCAPING DENVER spends those long days mowing, edging and trimming yards through Barnum and Westwood, then hauling the clippings away so the finished lawn is the only thing left to notice. Denver yards run small and stubborn — thin air, hard sun, ground that would rather grow buffalo grass than bluegrass — and they answer almost entirely to attention. Aeration opens the soil in spring, overseeding fills the bare places, fresh mulch darkens the beds until the color of the plants jumps forward. A yard like that is worth stepping outside for after supper.