Reports I've seen are that these seed shipments have false customs declarations, claiming that they contain something else, e.g. this one which was declared as "ring". That would violate 18 USC 542:
Whoever enters or introduces, or attempts to enter or introduce, into the commerce of the United States any imported merchandise by means of any ...
We have an intersection of two very different effects.
Agricultural import laws
This is an area of law that normally, consumers have no reason to deal with. However the laws apply to absolutely everyone connected with import of biological items like this.
Of course a recipient of unsolicited seeds has no reason to have learned any of this.
What scientists ...