St. Paul, Minnesota is corn country and corn grows everywhere here. Corn is a popular crop but you can not save seed from all types of corn. The corn must be an open pollinated variety or the seeds will not be good to use for growing.
Indian corn, popcorn, and some varieties of sweet corn can be used for seed the next year to grow new plants. Use corn from cobs that are well developed and look good. Let the cob stay on the stalk until the stalk starts to die or is dried out and brown. Then pick the cobs and open them up.
If the kernels are not completely dried you can let the corn cob sit in a dry place to continue drying out the kernels. If you are not sure if your corn kernels are dry enough you can wait until they are slightly wriggly on the cob before you take off the kernels.
When you have stripped the kernels off of the cob you can place them in a paper envelope and store them in a cool dry area.. Do not allow the corn seeds to freeze since it will kill most varieties of corn and they will not be good for growing new corn plants.
corn seeds will only last for a year so you will need to harvest new corn seeds every year. Corn can cross pollinate so you should only harvest corn from areas that are far from other types of corn plants.