I've looked into the Legality of this, and because Marijuana seeds have no THC, they are not considered illegal drugs under shipping laws. However, due to the Patriot Act, they consider marijuana growers "terrorists" (i'm not making that up) and are allowed to begin surveillance on you if they discover seeds being sent to your door. This is the Worst Case Scenario, and incredibly unlikely if you are buying seeds at a dozen or so at a time. You are below the DEA's budget's radar.
That being said, what would most likely happen is that Customs would seize your seeds and send you a note, explaining why whatever jurisdictional blah blah caused them to be confiscated, and a 'don't do that again'. Technically, since you didn't receive said goods, you didn't do anything wrong yet.
For as scary as it may sound, I've spoken to a lot of people that order seeds, and you are talking about a needle in a haystack. Customs is looking for explosives, nuclear material and drugs. Seeds are none of these things. If someone did notice, they'd probably just steal them and grow it themselves.
The biggest risk is losing your money. One, make sure the company is reputable. If yer still nervous, invest $14 in a PO box at one of those mailbox places. Use an older ID with an outdated address if you can, and never check the box at the same time of day, or you could just send someone who isn't you to scan the place for anyone who looks like a fed.
However, really, that last part...completely unnecessary for anything other than peace of mind. Which is important. It never hurts to cover your tracks.
Good luck, James Bond!