Which crop next in rotation?

I would like some advice on crop rotation. What organic crops are you planting in your rotation? I had Corn, soybeans and wheat in my rotation. I planted corn two years ago, then beans last year. I had planned to plant wheat last fall, but was not able to get my beans out in time, so I did not get wheat planted last fall. What should I do/plant next? Can I plant corn again, after planting it 2 years ago? Or should I plant a different crop this year? If so, what would you recommend to plant? In southern IA? Thank you, Randy