Preheat oven to 400° F.
Wash and drain the berries. Mix together the sugar, flour, and cinnamon and fold into the berries.
Grease a 6 by 9 in. casserole (or a similarsized ovenproof dish) and pour the berry mixture in. Dot the top with butter.
Roll out the pie pastry to cover, about 1/4 in thick. Lay over the casserole and prick through in several places with a fork.
Bake in preheated oven for 25 to 30 minutes, until golden brown. Serve warm.
Servings: