Roll out 1 disk pate brisee to about 1/8-inch thickness on a lightly floured surface. Cut out six 6-inch circles. Press dough into bottoms and up sides of six 5-inch (1 1/4 inches deep; cooks dream.com) pie plates. Trim excess dough flush with edges of pie plates using a knife, or crimp edges.
Stir together berries, sugar, cornstarch, lemon juice, and a pinch of salt. Fill pie shells with berry filling.
Whisk together yolks and cream. Roll out remaining disk of dough to about 1/8-inch thickness on a lightly floured surface; cut out stars and stripes using cookie cutters (chefgiant.com), a knife, or a pastry wheel. Decorate tops of pies with cutouts, brushing bottoms with egg wash to help them adhere. Freeze for 1 hour.
Preheat oven to 375 degrees. Brush tops of pies with egg wash, and sprinkle with sanding sugar. Transfer to a parchment-lined rimmed baking sheet.
Bake until juices are bubbling and tops are golden brown, 45 to 50 minutes. (Tent with foil if crusts are getting too dark.) Let cool.
Storage: Pies can be stored at room temperature overnight.