I've never sent weed through the mail yet..
But what I would do is put the bag/nuggets in a coffee pouch. One of those fron the grocery store. and re-seal it.
Then add a few other items,like some regional jam or books or cd's, and call it a care package.
I doubt they'd ever check it.
I've worked for both the USPS and UPS for a couple years.. Unless its totally obvious, they won't check.