Clean collards by removing tough stems. Wash thoroughly to remove any bugs or sand grit in the collards. Tear in pieces. Rinse corned pig tails well. Add to a large pot of boiling water and return to a boil. Once water has boiled add the collards and return to a boil (you may have to repeat this several times to get all the collards in the pot). Add fried chicken grease and red pepper flakes; cook until collards are tender. This usually takes 1-1/2 hours. During the last 15 minutes of cooking time you may add Cornbread Dumplings if desired (recipe to follow).