where do you live? unless you're in the EU outside of the UK, you'll be very hard pressed finding a shop that will ship mushrooms to you (for instance, if you're from the us, the uk, or canada) and if you DO find a site that will, and some will, they SHOULD NOT BE TRUSTED no matter WHAT. some people WILL send them, but its probably one of the worst ideas you could have. if you're thinking about amanita muscaria mushrooms...then whatever, good luck. anyway, you dont want a headshop for this, you want an "ethnobotanicals" vendor. there's plenty to choose from, and most have both good AND bad reputations depending on who you ask, so just go for it. i think www.sagewisdom.org is supposed to be good, though.
please feel free to scroll up and go to the "show your piece" section and looka t my thread titled "a list of online headshops"