Are they legal to ship to the US? I doubt they are, but on seeds for example, it has "shipping restrictions: United States" (or something like that). I didn't see that anywhere when I was looking at the mushrooms. Where I live, Mushrooms are extremely hard to come by, and it'd be sweet if for some reason the ones on GC were legal in someway.
psilocybin mushroom spores aren't illegal to possess, but if the DEA thinks you're gonna be usin em to grow shrooms, they can stop it. My advice, don't buy a grow box kit, because that tells them you're gonna grow 'em, instead make yourself a grow box with parts from a hardware store, and buy the spores separately. you can find grow box designs online at http://www.shroomery.org/ so it breaks down like this: anything containing psilocybin (including shrooms) are illegal, so don't buy em spores aren't illegal, except in california and georgia grow kits, the DEA will probly seize it, so you'll never get it