The Dogtooth Violet or Erythronium dens-canis is one of the first plants up in the spring.
First you see only the leaves, lovely green with reddish markings, spreading over the ground. And then come the flowers, only for a few precious days. It seems to take several years before the plants are mature enough to bloom. I have other patches of the leaves coming up every year, but those areas have no flowers yet.