Morgon-Monroe State Forest- A few miles east of 37 between Martinsville and Bloomington. Great trails, not too busy, campsite that is primitive. Also, you can camp for free in the "backcountry" but that is really designed for backpackers- although there is a spot where you could park and just carry your stuff a few hundred yards. I've done a few short hikes and a 2 day hike with my hound there. The trail that I was on for my 2-day actually is almost 40 miles long and runs into Yellowood State Forest near Nashville, where I've done day hikes. Around Bloomington there is no shortage of fantastic hikes. But, if you are coming from Lafayette, Morgan Monroe is the closest and is not inferior to any of the other park. For me, the biggest benefit is that the State Forests always have less people than the State Parks.
Potato Creek, Northcentral Indiana. A great place to take a walk through the woods. I go 6 or 7 times a year and now that it's perfectaly permissable to cary a gun, I just smile at the people
knowing I am safe.