you might try bush beans-- you should be able to get a
picking in before frost. or zucchini/summer squash. both are pretty quick to set fruit.
and then interplant with spinach in late august for when you pull the beans in the fall.

diggerb

Below is a link to the last planting dates for northern and southern Indiana.

Maybe it will give you some ideas of what to plant and when.

Sue

Here is a link that might be useful: The Fall Vegetable Garden