It has been raining marshmallows in suburban Detroit. A helicopter dropped thousands of the gooey sweet treats onto a park in Southfield Friday in the annual Great Marshmallow Drop. Hundreds of children waved and cheered as the helicopter passed by on its way to the drop zone. Once there, a passenger dumped the treats out of a sack and onto the grass below as children ran to snatch them up. But officials stressed that the fluffy sweet treats are not for eating: Kids exchanged the marshmallows they collected for a prize bag containing candy, a coloring book and a one-day pass to a water park.