In Fire Emblem: Fortune's Weave, you can collect pepper leaves from some nodes far from Dagsion. While there's a chance of one of these leaves could come in a crate, the best approach when you want to guarantee that you will have the material is to go to the world map, visit the right nodes and use the "Search" command — at least, this is the best way to obtain this specific material and complete Leda's "Captains' Drink Recipes" quest.