Preheat oven to 350°F. Grease a 9-inch deep-dish pie pan.
In a large bowl, combine the blackberries, 1/4 cup sugar, flour, cinnamon, nutmeg, and salt. Stir to combine.
Roll out the bottom pie crust and transfer it to the greased pie pan. Pour the berry mixture into the crust.
Roll out the top crust and place it over the berry mixture. Crimp the edges of the crust together and cut several vents in the top to allow the steam to escape.
Brush the top of the pie with milk and sprinkle with the remaining sugar.
Bake for 45-50 minutes, until the crust is golden brown and the filling is bubbling. Allow to cool before serving.
Interesting Facts
Wild blackberries are often found in the woods and fields of North America.
Blackberries are a rich source of dietary fiber, vitamin C, and antioxidants.
Pie has been around since the ancient Egyptians and Greeks.