Preheat oven to 325 degree F. In a medium mixing bowl stir together flour and sugar. Using a pastry blender, cut in butter until mixture resembles fine crumbs and starts to cling. Stir in lavender. Form mixture into a ball and knead until smooth.

Roll or pat dough on an ungreased cookie sheet into an 8x5-inch rectangle. Cut into 1-inch squares or diamonds. Separate the cookies on the cookie sheet.

Bake for 18 to 20 minutes or until the bottoms just start to brown. Transfer to wire racks covered with waxed paper to cool. Dust with powdered sugar. Store in a tightly covered container at room temperature for up to 3 days or in the freezer for up to 3 months; thaw at room temperature before serving. Makes about 40 square cookies or 30 diamond cookies.