Dissolve yeast in warm water with salt and sugar. Add 2 cups flour, beat well. Add melted shortening, mix well. Add 1 cup flour, mix well. Knead on floured surface. Place dough in oiled bowl. Let rise 30 minutes. Makes 2 medium crusts or 1 large crust. Top with desired amount of pizza sauce, mushrooms, pepperoni, and cheese. Bake at 450 until cheese is melted and golden brown crust.