Cream shortening and sugar; add eggs. Mix thoroughly. Sift together flour, baking powder and baking soda. Add to creamed mixture, alternating with sour milk. Beat 3 minutes. Stir in vanilla and peanuts. Mix thoroughly. Bake at 350 degrees for 50 to 60 minutes in prepared 9 x 13-inch pan. Frost, then sprinkle with reserved peanuts.