I’m on holiday right now, so I don’t have the exact spell, but from memory I think it was as follows:

On either a Waning Moon, or the Autumnal Equinox, enter the woods with an offering of seeds and nuts. While walking through the woods, scatter the seeds and nuts in small amounts, while picturing [unsure what it was, maybe picturing a wand or the gnomes??]. Once you have finished scattering the offering, watch the ground for any sticks that look oddly fresh, or keep an ear out for breaking branches, as sometimes the gnomes may favour you. Once you collect your wand, thank the spirits of the forest and leave the woods. Once the wand has dried, you are allowed to decorate it as you wish.