Contact any Veterans Affairs Administration hospital in your area. Illinois VA hospitals keep a small library for their patients and welcome new donations.
Research libraries in your Illinois community. Libraries in the Chicago and Urbana-Champaign usually operate non-profit bookstores and regularly hold "Friends of the Library" events. These events directly benefit the public library system, by funding new acquisitions and administrative costs.
Call second-hand bookstores, like Books at Sunset in Elgin, Illinois, or Top Shelf Books in Palantine, Illinois. Though these bookstores might have limited space for new books, most will welcome taking a look at popular books in good condition.