Remove 1/4 of the dough to use for the top of the pie.
Refrigerate the dough for 20 minutes to help it become firm.
Roll the dough out to fit to the pie plate. Trim off the extra dough.
Use a fork to decorate the edges of the pie crust.
Make the pie filling by combining the sugar, cornstarch, and salt. Move a small amount of the cornstarch mixture into another bowl. Add the strawberries to the larger amount and add the blueberries to the smaller amount.
Roll out the smaller amount of dough and cut the lines of the flag and use a small cookie cutter to make the stars.
You can brush milk or an egg wash over the dough to create a golden brown color. You do not have to do this step.
Bake the pie in a preheated 400 degree oven for 10 minutes. Reduce the temperature to 35, rotate the pie and back for 20-30 minutes.