Preheat oven to 450 degrees. Combine flour, poppy seeds, baking powder, sugar, baking soda, and salt. Cut in vegetable shortening and butter. Stir in buttermilk.
Knead dough four or five times. Pat out dough 1/2 inch thick.
Using a long sharp knife, cut dough into squares or rectangles.
Bake on ungreased baking sheet until golden, about 12 minutes.