Ceanothus (most likely) spinosus

The flowers, fresh or dried, contain saponins and can be used for their mild soapy qualities. It's the very tough roots however that are an unsung, very easily-found medicine, with a particular affinity for the lymph system and nodes. The tincture or a strong decoction can be used as a gargle for acute tonsillitis and as an adjunct herb internally for both mastitis and mononucleosis. Due to its anticoagulant properties this plant medicine is contraindicated for people on anticoagulants or with coagulation disorders.