Pick all but a few of the pea pods from your plants at the end of the season. Leave just a few pods on the vines until the absolute end of the autumn, until the pods are completely dry and brittle.
Spread old newspaper over a basement floor, unused counter or enclosed porch area. This will give you room for the peas to dry further before packaging.
Pick the remaining pea pods from the vines. Spread the pods over the newspaper sheets in a single layer. Leave a little bit of space between each pod so air can get to all sides of the pods. Allow the pods to dry for two weeks.
Shell the seeds by breaking apart the pods and shaking out the seeds that are inside. Pour the seeds into a clean and dry glass jar as you shell them.
Place a small spoonful of powdered milk onto a swatch of paper towel. The exact amount of milk doesn't really matter, just eyeball about 1 tsp. Pull up the edges of the paper towel and twist them together to make a pouch. This pouch with powdered milk will absorb any stray moisture from the beans in the jar and keep the beans dried.
Screw the lid on the jar tightly and place the jar on a shelf in your refrigerator. Leave the seeds in the refrigerator until next spring when it's time to plant your next garden.