Sassafras
Sassafras is a tree native to North America. Like pokeweed, the Native Americans had used it for centuries, and to the colonists, it was a particularly useful bit of flora. The leaves were fragrant and used to make a lovely tea. It was also added to stews and Creole dishes like gumbo.
Not quite as wholesome a use, it was also a very popular syphilis remedy in England in the 18th Century, and so large quantities of it were exported back home from the colonies during that time. Any data on how effective it was is patchy, however.