IMPORTANT CORN CAN GET YOU UNLIMITED DONUTS ACCORDING TO CODEBREAK1337.
He says after harvesting the corn, click on Cletus 10 times and you will get 100 donuts. then put you farm in inventory, take it back out, and tap on Cletus 10 times again for 100 more donuts. according to him, you can continue the process and get unlimited donuts. I have 70 days to go on my corn. Please let me know if it works!