Yellow ranks of milkweed, their pods bursting with seeds, line the edges of our fading wildflower field where they stood sentry all summer. I spent years encouraging them to naturalize and, now, along with the lupines, echinacea, and blue lobelia, they routinely come back and spread a little farther every spring. At full height, they’re ungainly plants, to be honest. Pods, leaves, and flower...