How much does a marshmallow weigh? no
I do not have a regular sized marshmallow on hand to test it out, but according to an onliine nutrition site, a regular sized marshmallow weighs 7.2 grams. If you are in the US, grams may not mean much to you, so I will say that a pound is 454 grams, which means that a marshmallow weighs very little indeed.
I can't guarantee that this is the right weight, as I have just weighed 10 mini marshmallows and they weigh 5 grams whereas this site says they are supposed to weigh 7 grams.