Get yourself a Delorme Atlas for Illinois and start finding some creeks. I'm looking at mine and looks like there are lots of creeks and streams near you. Just get an atlas and start finding creeks with public access. I've lived here all my life and I'm still finding places I've never been to with this little atlas. Great detail.
As for collecting, large dipnets like Jonah's Perfect Dipnet and even large aquarium dipnets work really well. If you have the opportunity, try it at night with a flashlight. The fish don't see you very well and very easy to catch. Another option is to get some very small hooks, preferably barbless and go fish for some.