Cream butter, sugar, eggs and vanilla. Add dry ingredients alternately with sour milk. Mix well. Fold in rhubarb, strawberries and pecans. Spread in a greased 9x13 pan. Bake at 350 degrees for 45-50 minutes or until browned and toothpick comes out clean. Ovens vary. Serve with Cool Whip or ice cream.
*To sour milk, add 2 tsp. vinegar to milk.