Filling: Toss the blueberries with the 1/2 cup sugar or more and lemon juice. Pour into a 13X9 inch oval baking dish.
Topping: Combine the cornmeal, flour, 1/2 cup sugar, baking powder, cinnamon, and salt in a mixing bowl. Make a well in the center and pour in the buttermilk, melted butter, and beaten egg. Stir with a wooden spoon to blend and then mix with a fork only until the batter comes together.
Drop the batter by spoonfuls on top of the blueberries in the pan. Bake the cobbler for 40 to 45 minutes or until the filling is bubbly and the topping is firm.