What international border problem for pollen? There really isn't one.
Seeds are fine to send by mail, though they may, MAY be confiscated or quarantined in the worst case scenario. I know people who have wild collected seed from parts of Malaysia/Indonesia and freely brought it back to the US, with both governments knowing, and neither caring. Pollen cannot grow into a plant on its own...its "less dangerous", and less restricted..if at all. In fact, you don't even need anything apart from a phytosanitary certificate to import plants into the US in certain cases*.
*It is ok with only a phytosanitary certificate if it is done VERY sparingly (I think theres actually a limit, which is probably only once), and the plants will be used for research/personal growing. If you plan to resell them, you need permits. If you import frequently, you need permits. Many people LOVE shoving laws in your face that they themselves have no idea about, they have just "heard" that (bottom line) "its illegal" and "the paperwork takes soooo long and is sooooo expensive and is soooo not worth it". Please...its ONE piece of paper (front side only) to get an import permit.
Yes, I have actually had a lawyer speak with the people from the USDA...so my claims are valid.