There isn't much and what there is probably won't be too impressive. There is the Indiana Green Expo in Indianapolis in January and there is a new show put on by the Illinios/Wisconsin Landscape Assn's held in Schaumburg IL. I believe that is also in January.
There used to be the MidAm show in Chicago, which at one time was a great show and then when they moved it from Navy Pier to McCormick it died and was buried (canceled permanently) after the 2014 show. Your best bet is making the trek to Louisville in Oct for a really good show.