Midland Shootingstar (Dodecatheon meadia), one of about a dozen or two shootingstar varieties, a type of primrose, is a popular wildflower found throughout the eastern US, including most Illinois counties, and a really cool perennial.
For more about Midland Shootingstar and native plants for the Midwest, especially those that do well in shade/moist areas, see the "book" on this website, Gardening with Native Plants in Shady Evanston.