well if they are knocking and not busting in don't let them in for any reason without a warrant but just keep very calm and corporative saying things like, officer, i want to help you in anyway that i can but unless you are here serving a warrant i'm confused as to what this is about?
If they have a warrant you made a mistake along the way, probably a huge one or several little ones along the way usually by way of mouth and its to late no matter what you try and do other than trying to beam them up scotty.
It is ridicules that this God given plant is illegal to the point the "crime" would cause a jail sentence. That is insane.