Ask Mr. Smarty Plants

If your bluebonnet is Lupinus texensis (Texas bluebonnet), it is an annual and its plants will die during the winter.  If you allowed it to drop its seeds, it could possibly grow again from them for next spring, although it is out of its natural range (see the distribution map from USDA Plants Database).  In Texas the tiny rosettes of the spring plants have already appeared from the seeds deposited in spring and summer.  They will overwinter and begin to grow taller after the warm spring rains and produce flowers in late March through the month of May.  The Texas bluebonnet grows as far north as Oklahoma where the USDA Hardiness Zones 6 and 7.  Since Mason City is in Zone 5a, the seeds may or may not germinate there.  If you grew your bluebonnets from seeds for this year, then it may work.  They should be in the ground by now, however.   Here is a a How to Article, How to Grow Bluebonnets, that gives more details.

As an alternative to the Texas bluebonnet, there is a beautiful lupine, Lupinus perennis (Sundial lupine), that is native to Illinois.  It is a perennial and blooms in May and June.  You can check our National Suppliers Directory for nurseries in Illinois that specialize in native plants that might carry seeds for the sundial lupine.  In a quick check I found that Wilson Seed Farms, Inc. in Tiskilwa, Illinois has seeds for sale.