Lay out the pie crust in a floured surface and roll it out with a rolling pin to fit your 9-inch pie dish, then transfer it carefully into the dish, pressing gently against the edges. Trim excess crust along the rim.
In a mixing bowl, combine the berries, granulated sugar, lemon juice, and flour. Gently toss until the berries are evenly coated and mixture appears slightly thickened. Let sit for 5 minutes to allow juices to meld.
Pour the berry filling into the prepared pie crust, spreading it evenly with a spatula. The filling should be heaping but contained within the crust edge.
Cover the pie with the top crust or create a lattice pattern. Trim and crimp the edges to seal. Make small vents in the top crust if using whole cover to allow steam escape.
Bake the pie in a preheated oven at 375°F (190°C) for about 40 minutes, or until the crust is golden brown and filling is bubbling through the vents. You should hear a gentle bubbling sound and see a rich golden color develop.
Once baked, remove the pie from the oven and allow it to cool for at least 15 minutes. Serve warm or at room temperature, optionally with a scoop of vanilla ice cream or whipped cream.
