This substance is now considered an illegal drug and as such it should be viewed that way in your dream interpretation. As a symbol, it stands for any activity that is not within the bounds of the law. It can also denote the fact of not being able to think clearly if you dream that you are smoking it, and this could cause you much trouble and stress. As an herb, it has curative powers, and for the older generation of dreamers who still think of this as an herb, this is a warning to have your health seen to by a professional.