Tansy

According to my good friend Prof Google, Tansy Tanacetum vulgare is a perennial, herbaceous flowering plant in the aster family. It is  native to temperate Europe and Asia but it has been introduced to other parts of the world, including North America, and in some areas has become invasive. 

Tansy leaves were traditionally eaten at Easter to help kill off the worms that the diet of fish at that time caused. They were quite bitter, so were mixed with eggs, milk and flour in a kind of pancake or omelette.
In addition to medicinal applications, common tansy has been used as an insect repellent since the Middle Ages to modern times.