PenniF

I bought cupcake boxes at JoAnn's in the Wilton section. I put the cupcakes in (put a large marshmallow in the center to help with shifting) then gently laid plastic wrap over them and put a bit of paper Easter grass on top....just enough so that the cupcakes could not move up and down...the box pretty much keeps them from moving side to side.
I then boxed them with packing material to keep the cupcake boxes from moving around and sent them priority mail.
These are done with mini marshmallows on top, but most frostings get a surface on them after they sit a bit, so you should be able to do the same thing without the plastic wrap sticking to the frosting.