It's highly unlikely in either case, and I've not heard of it yet either.
But let's say for instance that you live in Georgia and ordered from Colorado and somebody at the post office discovered the shipment. Well, what you're going to have is a state to state destination. They're going to know exactly where the package came from and where it's going to.
At that point, if they were going to do anything at all, they'd let the package go on to it's destination: you.
Once that package was delivered, Federal Authorities would probably wait a day or two then serve you with a search warrant and go from there. They'll find your shit. You'll be charged with transporting across state lines among probably several other things and be offered a deal if you rat out who sold you the seeds. Then of course they'd raid the place that sold you the seeds.
Everybody would get it right in the ass.
But when you order from overseas, it goes to international customs first. If it's caught there, they're not permitted by law to let it go any further. They wont really have any way to go after who sent them because all they're going to have is a nation of origin. (In my case, Amsterdam, where it's legal.)
It ends right there. Nothing happens to anybody.
If it clears international customs, that's it. It's not examined by anybody else because there's no need to.
It's just like visiting a country. If you go through customs when you land at JFK, you don't have to do that again when you get to Atlanta. You do it once and that's it - nobody cares or looks after that.