Place potatoes into a large pot and cover with salted water; bring to a boil. Reduce heat to medium-low and simmer until tender, about 20 minutes. Drain and transfer potatoes to a large bowl; mash coarsely, then set aside.
Preheat the oven to 400 degrees F (200 degrees C).
Heat oil in a large skillet over medium-high heat; cook and stir onions, coriander seed, curry powder, ginger, salt, turmeric, cumin, allspice, cayenne pepper, and cinnamon in hot oil until onion is lightly browned, about 5 minutes. Remove the skillet from heat and stir in tomatoes and peas. Pour into coarsely mashed potatoes and mix until thoroughly combined. Cool filling completely.
Cut each pie crust into 8 equal triangles. Spoon filling onto the wide end of each triangle; fold corners over filling to create a triangle-shaped hat. Pinch dough together to form a seal. Brush beaten egg whites over each samosa and arrange on baking sheets.
Bake in the preheated oven until samosas are golden brown, about 15 minutes.