Crafting Materials are any item whose main purpose of existence is to be used to craft / create something else in game. Most crafting materials come either as 'Raw materials' which could be harvested via certain Weapons (basically tools, but currently linking to weapons as they can be wielded as such) or defeating certain monsters; or as 'Processed materials' which are made when you process a group of raw materials together, but they themselves are only meant to be the in-between step before being used for a practical item.
Due to this, it would make sense for food items to be listed under Consumes, as they do allow consumption, even though they could be used as a cooking craft material. (Perhaps one can work on that once we have more cooking recipes?)
The following list is INCOMPLETE, and could use help. As more items become discovered, I would like to separate this table into different categories (ie: herbalism, woodcutting, mining, tanning)