There are some very knowledgeable posters here who have said it is legal to take it, so I am going to disagree with a bit of trepidation - but it is my understanding that in the United States there is a caveat based on religion. Any infringement upon religious freedom is simply one of those libelous acts that even the prison system avoids.

I am Native American and have brought my medicine pouch in to a hospital stay. I allowed them to go through it, without touching - I removed each item, explained its significance, and returned it to the pouch. It probably helped that I had a letter from a friend on his attorney letterhead explaining what it was.