Nightshade will be found in almost anywhere in the kingdom that is shaded by trees or is dark and dank. Be aware that nightshade may only be found in one clump, and not in several bunches where it is dark or shady. Two specific locations that I have found nightshade in are behind the wizard's tower under a tree and in front of the cave. Remember, only Physicians and Wizards can harverst nightshade. You may also be able to buy it at the village shoppe.
Hope this helps.
