Place oats in a food processor; pulse 5 to 6 times until oats resemble coarse meal. Place in a large bowl.
Weigh or lightly spoon flours into dry measuring cups; level with a knife. Add flours and next 5 ingredients to oats in bowl; stir well with a whisk. Make a well in center of mixture.
Combine buttermilk and next 3 ingredients in small bowl; stir well with a whisk. Add to flour mixture, stirring just until moist.
Toss berries with 2 tablespoons flour, and gently fold into batter. Spoon batter into 16 muffin cups coated with cooking spray; sprinkle 2 tablespoons granulated sugar evenly over batter. Bake at 400° for 20 minutes or until muffins spring back when touched lightly in center. Remove from pans immediately; place on a wire rack. Serve warm or at room temperature.