Now is the time to gather your sassafras leaves to dry for filé powder. Danno has a great post on filé powder at NolaCuisine.
Gather your leaves on stems in the early evening in mid-August in mid-America--hang upside down in paper bag to help keep them free of dust and to catch any leaves that may fall. When the leaves are dry, remove from stems and crush. Store in an air-tight container--the leaves contain a volatile oil. Use in stews and gumbos to add a certain thick richness to the broth. Do not add until the stew is almost done, and do not boil after the addition of the filé. Enjoy.
As an aside--sassafras roots are an ingredient in modern rootbeer.