Heat oven to 375°F. On ungreased cookie sheet, unroll pie crust . Place meatballs on center of crust.
In small bowl, mix corn and 1/2 cup of the salsa. Spoon corn mixture over meatballs. Fold edge of crust over filling (about 2 inches); ruffle decoratively.
Bake 35 to 40 minutes or until crust is deep golden brown. Sprinkle with cheese. Bake 3 to 5 minutes longer or until cheese is melted.
Top with lettuce and sour cream. Drizzle with remaining 1/4 cup salsa. Serve immediately.