Well... actually, you do need either spores or a piece of living mycelium or a piece of the fruit body of a mushroom.
But I think what chalkolate was trying to convey is basically the same here: you can't just expect mushrooms to popup out of the vermiculite. They need to come from somewhere, and this is typically spores, but you can also just take a slice of a mushroom or another culture and use that to colonize your substrate.