Greetings Fellow Alumnas!
Your absolute best bet is to contact a professional consulting forester seeing that you have 300 acres of forest land with numerous black walnut trees.
Based on what you've described, you easily should be able to derive periodic, sizeable income potential from this property if you manage it wisely -- which means, work with a professional forester, develop a forest management plan, and market your timber.
The following Website will link you to a list of IL-DNR foresters and private consulting foresters -- call them up and explain to them your goals and objectives for your property.
http://dnr.state.il.us/conservation/forestry/
IL-DNR foresters typically have a waiting list, but their service are free. Whereas professional onsulting foresters charge a fee for their services; however, their fees are well worth the money because you will typically make 25-250% more from your timber sales.
Market your timber the right way -- contact a professional forester first!!!
Best of luck to you!