your post just does not make sense. If the folks at the post office at any point thought the package coming to you was an issue, it would have been inspected/discarded ect and never delivered to you. The SENDER would have been fined for not complying with the states laws re shipping for nurseries ect. Not you.
However, AFTER, it was delivered to you, how then did they know they should not have delivered it to you? and how did they show up at your house? Also, why did you let them in to see anything? When weird strangers show up at my door demanding to see my personal belongings, they will be told to produce a warrant or leave my property. The entire scenario does not seem plausible unless I am missing something here.
