Aside from mostly being useless or mundane (e.g., wooden poles), there are outright silly items.
For example, in a deep Vault, a Fey Chest contained Bread Dough.
Recommend maybe giving a theme to the chest contents, such as materials that only Fey or Bound normally have, e.g., Lacunus ingots or parts, maybe materials to make enchantments and cards.
Or invent something that can give us some insight into the Fey, like fey foods or clothing or materials.
Chests wtih cards would be much better if they weren't so easy to craft/research.
Another fey chest with silly/useless contents. It is more valuable to destroy the chest and collect the materials.