If you're traveling I-70 past Richmond, IN there are two little places that serve great food.
Little Sheba's is an intimate place with great atmosphere. Located in a former butcher shop, their menu contains over 3 pages of unique sandwiches. Their soups are wonderful (Wisconsin cheese soup, etc.). Closed on Sundays.
Also try El Rodeo. They have both East and West side locations. The owner and all employees are Mexican. I lived for two years in Mexico and I can vouch for the authenticity of their menu. Open 7 days a week.
You absolutely can't go wrong with either choice.