Combine buttermilk and cereal; set aside. Sift together flour, baking powder, soda, and salt. Cut shortening into flour mixture with a pastry blender until mixture resembles coarse meal. Add cereal mixture, stirring with a fork until dry ingredients are moistened.
Turn dough out onto a floured surface; knead 4 to 5 times.
Roll dough to 1/2-inch thickness; cut with a 2 1/2-inch biscuit cutter. Place biscuits on a greased baking sheet. Bake at 400° for 12 minutes or until biscuits are lightly browned.