@Frillilily I have never heard of that happening either. Usually if a package is going to be held for quarantine or destroyed, it is pulled at the point of entry into the state it if shipped to when it is first sorted or when it is first discovered in the shipping path. They used to use the 'beagle squads' here, at least in Miami, those dogs sniffed the mail and caught out illegal food, plants and drugs. Now they may randomly Xray things post 9/11. I don't know. But I too never heard of anyone coming to your house. Usually they send you a letter (if you are the SENDER) and detail what they did or intend to do....ie we seized your box at XX location on entry into XX state the contents were found to violate XX statute(s) the contents were either 1. destroyed 2. held for quarantine and released.
And if your violation was specific against certain statutes it delineated what you had violated and when the punishment would be (warning, fine, forfeiture of nursery license, court date)
I do know that there have been cases of people who buy illegal animal parts, feathers, and bones, especially from endangered species, who have been visited and the items confiscated and the person prosecuted. It is believed that you are just as guilty as the seller in that instance and should have known better. Just like for plants there are lists by state of what animal parts are legal to ship where and what is forbidden.
I do know that 10+ years ago, a guy in Texas was caught sending water lettuce through the mail. Water lettuce was illegal to have or to sell in Texas and the state he sent it to had also banned it as a noxious weed. He was fined $2200 PER PLANT for that mistake. That was a huge deal on forums back then, it was a very cautionary tale