No problem: INstead of corn have a starchy food like potato, or have sweet potato, or substitute bread.
Peanuts: Try Brazil, hazlenut, walnut, pecan, or almond. You can find nut butters made from these too.
Watermelon cantelope: Peach, strawberry, blueberry, apple, plum, pear or other. Organic is expensive, so split fruits with your family and have bites rather than entire fruits.
For every food I ruled out, I added a couple I didn't usually eat, so I think my total number of foods has increased instead of decreased.
Over time, I think you can do this. Lots of foods were created for you.