Combine the pineapple chunks, mandarin orange segments, shredded coconut, mini marshmallows, and optional cherries and nuts in a large mixing bowl.
Gently fold in the sour cream and whipped cream or whipped topping until all the ingredients are well coated.
Cover the bowl with plastic wrap.
Refrigerate for at least 2 hours, or overnight, to allow the flavors to meld and the ambrosia to chill.
Before serving, give the ambrosia a gentle stir to make sure all the ingredients are evenly distributed.
Serve chilled in individual dessert dishes or as a side dish.
Optionally, you can garnish each serving with a fresh cherry or sprinkle some additional shredded coconut on top for added visual appeal.
Enjoy this delightful and refreshing ambrosia!