Regardless, you should NEVER inject anything that contains proteins foreign to the human body (OK, some insulin is from pork or beef sources, but it is pretty much identical to human insulin). Psilocybe mushrooms come from a completely different class of living creature (animals, plants, fungi & bacteria), so will contain proteins that will make the immune system go into overdrive, possibly causing fatal anaphylaxis. Same goes for plant material.
Whether or not the story is true, I thought I should remind people that doing such things is a good way to die horribly...