OPEN and DRAIN the cans of fruit. No need to rinse, but you do need to drain. If you have time, drain the fruit in a strainer for 30 minutes.
WASH the grapes and then CUT them in half.
REMOVE the maraschino cherry stems if they are still attached. CUT the cherries in half. Reserve a few whole cherries to place on top of the salad.
WHIP the heavy cream. Pour the heavy cream into a cold bowl and whip using a hand mixer with a wire whip attachment for 4 to 5 minutes, or until the cream is whipped to soft to medium peaks.
MEASURE the sour cream. MIX the whipped cream into the sour cream.
SWEETEN with sugar (optional).
STIR the mini marshmallows, shredded coconut, and nut tidbits into the whipped cream/sour cream mixture.
STIR in the pineapple, grapes, and cherries.
ADD the mandarin oranges and stir to combine. When you add the oranges last, they are less likely to break apart.
CHILL at least 2 hours and up to 24 hours before serving. This chilling blends the flavors, chills the fruit, and moistens the marshmallows and coconut.
SERVE cold with a cherry on top.