Formerly used as a cure-all medicinal herb, agrimony leaves are 'still used as a stimulating alternative to tea'. (Reader's Digest Field Guide to Wild Flowers). I've not tried it myself.
It was thought to be magic and so was called 'fairy's wand' or 'fairy's rod', which was later changed to 'Aaron's rod' when the early church was discouraging pagan beliefs.
Once the flowers are over, the seeds develop into little burr-like balls, similar to goosegrass fruits. They attach themselves to the fur of passing animals or human socks and shoe laces, and so the seeds are distributed widely.