I have tried to use this idea 2 years in a row and every time I get around to it I have to go off for a week or two. So I will share this with whoever would like to try to build it.
Take some whole coriander seeds and paint them with some nice pumpkin orange paint. Now to make Great Pumpkins use some pepper corns. For tiny ones use mustard seeds. Throw them in a wagon or make a roadside stand (I wanted to use the german market stands sold by a couple of folks in Europe) add a sign and some fall trees and folage, perhaps a scarecrow and and some cornstacks, and you got a prize winning Halloween diarama.
Back of a farm truck or a farm wagon would work too!
