Hi Scarlett, I was checking that out on NORML's website recently, too. If I understand correctly, it's just a way of adding an additional penalty when someone's arrested & charged with possession. Not only do you get charged with the crime for possession, but you also get a fine (or maybe charged with tax-evasion?) for not having the stamp... It's just another f**ed up way for the government to screw you for being in possession of god-given plant material! I'd like to collect them, too, but I don't know if you can actually go buy one... I'd be too paranoid to try.