Place berries in a colander over a bowl to defrost and drain liquid.
Preheat oven to 425 F.
In a large bowl, combine berries, sugar, flour, cinnamon and lemon juice. Mix to combine.
Transfer to baked pie crust.
On a well floured board, roll out unbaked pie crust. You can go with a traditional top crust and cover completely or you can do as I did and use a seasonal cookie cutter to cut out shapes and place around as the top "crust". Brush the top with water and sprinkle decorative sugar on top, or just sprinkle a little regular sugar.
Cover edges of bottom crust with aluminum foil. Bake for 1 hour.
Cool and serve.
Serve with ice cream or whipped cream, if desired.
My crust is a little dark because it was only covered with foil for half of the cooking time. Your crust will be perfect if you leave it covered for the entire baking time.