Heat oven to 400°F. Generously coat standard 12-muffin pan with nonstick cooking spray.
Mix 2 cups flour, 1 cup sugar, baking powder, salt and poppy seeds in large bowl. With pastry blender, cut in butter until mixture resembles fine crumbs.
Lightly beat egg, milk, lemon rind and juice, and vanilla in small bowl. Stir egg mixture into flour mixture until just blended, Toss berries with 1 tablespoon flour in a bowl; fold berries into batter. Divide batter among prepared cups in muffin pan. Sprinkle top with remaining 1 tablespoon sugar.
Bake in 400°F oven 20 minutes or until tooth pick inserted in centers comes out clean. Run sharp knife or spatula around each muffin; remove from pan. Serve warm, if desired.