Yseralline Seed

Source
This item is gathered from the following herb nodes:


 * Aethril in Azsuna
 * Dreamleaf in Val'sharah
 * Fjarnskaggl in Stormheim
 * Foxflower in Highmountain

It can also be gathered from nearly all plant-type mobs in Val'sharah.

Alchemy

 * Ancient Healing Potion
 * Ancient Mana Potion

Cooking

 * Seed-Battered Fish Plate

Inscription

 * Mass Mill Yseralline Seeds

As a quest objective

 * Lining the Crucible