To freeze collard greens, first rinse them thoroughly with cold water; roughly chop them if desired. Next, boil a large pot of water. When the water is boiling, add the greens, using a spoon or tongs to make sure the greens are completely underwater. Cover the pot or turn up the heat level in order to keep the water boiling. Allow the greens to remain in the boiling water for 30 seconds.
Next, move the greens to a large bowl of ice water using tongs or a wire strainer. Let the greens remain in the ice water for two to three minutes, being sure to add more ice as necessary to keep the water cold. Then drain the water and ice, and squeeze the water out of the greens using your hands. Squeeze the greens a few times to remove as much water as possible.
When the greens are dry but still flexible, pack them into spheres, about the size of a baseball. Lay the spheres on a baking sheet, keeping even space between them. Tightly cover the sheet with plastic wrap.
After the greens are partially frozen, transfer them to a freezer bag. Remove as much air as possible from the bag, and seal it. Remove the spheres as desired to thaw, and enjoy.