[Sue]

If you write live plants somewhere easy to spot on the box many (not all) postal workers will take a little care.

I regularly ship and recieve regular garden plants and my mailperson knows to leave it in the shade someplace if I'm not home or hand it to me in person. The postmaster also takes his time if he knows they are live plants or seeds and hand cancels things. Maybe it's just a small town perk but it can't hurt.

 

[Sue]

Corigan, you need a phyto-sanitary cert from ag dept. They will come out and inspect plant material for a price, varies from state to state. Not worth it for most hobbiests.
Lot of aquatic plants are stringently controled, ie eurasian milfoil.

I suppose you could do the old ebay trick and label it as used clothing with a low, low value. Package leaks and the whole thing could get tossed or they come knocking on your door. Odds are high for just tossed.