There is a great deal of regulations and paperwork involved in moving
plant material across state or international boundaries. This system is
in place to help prevent the spread of insects, plant viruses, and plant
pathogens. I strongly recommend dealing with legitimate companies who
can legally ship you clean stock with the necessary phytosanitary
certificates. It may seem innocent enough to send a few sweet potato
slips in the mail, but customs would destroy the shipment if found, and
you really never know as a layman what kinds of laws you would be
violating and what the possible negative consequences your shipment
could cause.
Paul
[permaculture] Sweet Potato,
Paul Cross, 03/19/2014