In a large mixing bowl, combine the dry ingredients and the nuts. In another bowl, combine pumpkin, sugar, margarine and vanilla; add to flour mixture and mix well. Turn onto a lightly floured surface; knead slightly, adding flour until the dough is not too sticky. Pat dough to 1/2 in. thickness. Cut with a 2 1/2 biscuit cutter and place on lightly greased baking sheets. Bake at 400 for 15 minutes or until golden brown.