Lavandula or commonly known as Lavenders are flowers that that produces either grey-green foliages or purple and blue flowers in blunt spikes on a long stems. It's from the flowering family Lamiaceae and is native in the Mediterranean.
It's said that Lavenders are known for it's healing properties which might be the reason why tales about the Doctor of War & Grief has mentions of Lavenders in them. But Lavenders are best know for being an aromatic plant.
Other plants that tend to be mention to have less traumatic experience with the doctor are:
Coneflowers, Mallows, Star grass, Dandelion and Sage