Chamomile is an important ingredient in Dying Light 2 and is used alongside Honey to craft Medicine. This ingredient is first introduced early in the game during the Pilgrim’s Path quest where Spike requests you to gather some Honey and Chamomile found throughout the forest.
Chamomile can also be found on the Roof Groves in Villedor and is easy to spot thanks to its white petals and is surrounded by Beehives, UV Shroomz, Lavender, Cordyceps, and weapons.
Roof Groves are usually surrounded by Red/Yellow trees and are fairly easy to spot since you can use your Binoculars to find them from a high vantage point.
You can also explore other areas in Villedor to find Chamomile, you can also use your Survivor Sense to find it along with any other ingredients or quest items that you might need.