Ancient BarkPick it up to discover it.
IronPick it up to discover it.
Ymir FleshPick it up to discover it.
Draugr Elite TrophyPick it up to discover it.
ForgeDiscover and use at level 2 or higher.
Discovery is separate from having enough materials to craft. Check shelter, fire, placement, and station access in-game. This checklist cannot diagnose broken mods or save files. Each alternative recipe is listed separately.