Safrole is a simple organic compound found in sassafras oil.
It has a pleasant odor and used to be used to flavor root beer, but sassafras oil has fallen out of favor in the past few years for a few reasons: first, safrole has been deemed carcinogenic and banned as a flavoring agent by the US FDA. Second, it’s actually a drug precursor – like pseudoephedrine-containing allergy medicines, it’s not illegal to buy sassafras oil (as far as I know, I’ve never tried!), but it’s watched closely by US drug enforcement. The people buying pints at a time probably aren’t making a few gallons of root beer, and safrole-free sassafras oil is available for flavoring purposes anyway, so you might have some ‘splaining to do if you were to pick up a case.