Ben,
There are definite rules and some absolute exclusions if you go through a border inspection station.
Some trees are not allowed at all. Scots pine is one of them.
For Japanese black pine you will need to have a European pine shoot moth certificate.
Any of the trees that are considered carriers of Sudden Oak Death would need to have a USDA inspection certificate. Azaleas are on that list.
The California dept of ag probably has a website.
Good luck,
Chris