I do not believe corns require cites permits, but other permits might be required.
A corn breeder up in canada might be able to tell you more, since they have probably imported corns on more than one occasion. Another possibility would be to ask one of the big corn breeders in the US that do a lot of online business, because they probably get international orders.
EDIT: I found this on Kathy Love's site:
http://www.corn-utopia.com/Corn%20Ut...ort%20%20(ONLY)