Crafting mats don't drop from mobs directly accept for hides from animals for the leatherworking side of clothier. They are mostly from harvestable nodes at the appropriate level to where you are playing for everything. Provisioning will find its materials from lootable crates, barrels, bags, etc that you can interact with.
How you get crafting mats from loot is deconstructiong the gear drops you get. This is also the fastest way to level woodworking, blacksmithing and clothier.
You can work your way up by spending skill points in your craft of choice to be able to do even the top level end game gear.
There are also upgrade items you get in the process of deconstructing things, sometimes in loot (rare), and via your hireling. These upgrade items allow you to upgrade from white to green, green to blue, etc as long as you have enough of the right upgrade element to make your chances good.
So its best to work out how we are going to share the items we are not going to use to help our fellow crafters - directly to those we know can use, just by letting first come first served get it out of the guild bank, or just pass on to those in the group at the time. Including handing over various loot items that might have a trait on them that you haven't researched yet. Every item you make can have one trait added, but you first have to research an item with that trait in order to make it.
Crafting in this game is pretty cool and is not simple cookie cutter where you learn recipes automatically at a given level. Even provisioners need to find recipes before they can cook.
