ambrosia salad recipe

1 can (20 ounces) pineapple chunks, drained - 1 can (11 ounces) mandarin oranges, drained - 1 cup mini marshmallows - 1 cup sweetened shredded coconut - 1 cup sour cream or Greek yogurt (for a lighter option) - 1/2 cup chopped pecans or walnuts (optional) - 1 cup maraschino cherries, drained and halved - 1 cup seedless green or red grapes, halved (optional) - 1/4 cup granulated sugar (optional, to taste)