These can be prepared a day ahead and stored in an airtight container.
Combine first 3 ingredients. Cut butter into flour mixture with a pastry blender until crumbly; add buttermilk, stirring until dry ingredients are moistened.
Turn dough out onto a lightly floured surface; knead 3 to 4 times.
Roll dough to 1/4-inch thickness; cut with a 2-inch round cutter, and place on a baking sheet. Reroll and cut trimmings, if necessary, to make 2 dozen.
Bake at 425° for 12 to 15 minutes or until lightly browned.
Note: We used Martha White self-rising soft-wheat flour.