Tim,
You are thinking of a Catalpa tree......they are not the same.
The KC tree is a fairly rare tree for Northern IL. I only ever remember seeing 3 of them in 50+ years afield. Most were large, open meadow trees that had survived the fence to fence clear cutting by farmers of the 70's.
They have a Johnny Appleseed history. During the Civil War, soldiers used to roast the seeds and brew a poor coffee from them. It is said that if you find a grove of them, it was a bivouac site and that trees out of the normal range were a result of dropped seeds by soldiers returning home.