||It is federally illegal to sell anything which you represent as opium or any other schedule I or II drug, regardless of what it actually is. The Federal Analogue Act says (among other things) that any substance :|
which [a] person represents or intends to have a stimulant, depressant, or hallucinogenic effect on the central nervous system that is substantially similar to or greater than the stimulant, depressant, or hallucinogenic effect on the central nervous system of a controlled substance in schedule I or II.
shall be treated as a schedule I substance (the most illegal category).
In fact it is also technically illegal to sell anything which you represent as having similar or greater effects to a scheduled drug, regardless of what you call it. While the second part of this is seldom enforced, it is included in the law.
Aside from the above, it's just a really irritating and unethical thing to do. The last thing we need is more people selling substances as something other than what they really are. It's hard enough for people to know what they're getting on the street without sellers intentionally misrepresenting their products just to make a buck. Please don't do it.