Harvest edible corn and leave two or three of the healthiest ears on the stalk. Wait four to six weeks after you have harvested the edible corn to allow the husks to turn brown and become brittle. Hold onto a dried ear and twist the ear away from the stalk in one movement. Collect all of your dried ears.
Pull back the husk of each ear the same way you would if you were shucking the corn for eating. But do not remove the husk. Tie a foot-long length of string around the husk that you've pulled back.
Hang each ear by the string tied around the husk in a warm place where it can finish drying. Leave all the ears in place for three months until they are thoroughly dry.
Hold a fully dried ear by the husk. Point it down and into a bucket. Starting close to the husk, use your other hand to twist downward and pop the kernels off the ear and into the bucket.
Continue to twist and work your hand downward on each ear to remove all of the kernels. Sift out debris that may have fallen into the bucket. Pour the seeds into a glass jar and seal it shut. Place the jar in a cool, dry place for storage.