In Springfield, there are lots of Abraham Lincoln sites; but your team might find this to be like Americans visiting Har Herzl or Sdeh Boker. My two favorites:
Abraham Lincoln Presidential Library and Museum:
http://www.alplm.org
Lincoln's Tomb:
http://www.lincolntomb.org
For a quick stop, weird outside "sculptures", and ice cream and snacks for sale: Pink Elephant Antique Mall in Livingston, IL:
http://https://www.google.com/maps/p...d2c9d6d95c7dbd
Also - FYI, I am Malka and Eli Glas' brother-in-law's brother. Let me know if I can be of any help!