We love all parts of this plant.  We grow it for the beautiful and delicious foliage, the seeds and the flowers.  We also let it self seed abundantly in the garden to provide a habitat for the black swallowtail's caterpillars.  
 
The seeds have a gentler flavour than the large green fennel seeds you buy at the store.  We love them in bread, crackers, or powdered into marinades. 
 
They also make a fantastic and effective digestive tea- simmer a heaping teaspoon of seeds in 2 cups of water for 5 minutes or cover with boiling water and let steep for at least 15 minutes.