Lightly grease twelve 2-1/2-inch muffin pans or line with bake cups. In a medium mixing bowl, combine cornmeal, flour, sugar, baking powder, and salt. Make a well in center.
In another bowl, mix egg, milk, and cooking oil. Add to the flour mixture. Stir until just moistened. Fold in berries.
Fill prepared muffin pans 2/3 full with batter. Bake in a 400 degree F oven for 20 to 25 minutes or until golden. Remove from pans. Makes about 12 muffins.
To make jumbo muffins, spoon into 3-1/2-inch muffin cups and bake in a 375 degree F oven for 30 to 35 minutes.