This is straight off that link. I am going to make my son some for Christmas with 49'er fabric. Hope I can find some!
The corn bags shall be made from two fabric squares with a quarter inch double stitched seam on all four sides. The corn bags should be made from 12 oz / sq yd duck canvas and may be any color that is easy to see during Cornhole play. Each bag shall be filled with approximately 2 cups of corn feed and finished bags should be a minimum of 6" X 6" square and weigh between 14 and 16 ounces.