Wood produced by large trees. People say it's almost as hard as some metals.
Ironwood can be gathered by chopping down normal large trees and Poplar Trees, palm trees, and cacti in the Desert. Ironwood can also be ordered from the Tree Farm after restoring it during Mission: Saving the Tree Farm.
Iron Wooden Plank
Composite Wooden Board
2 Tree Sap
Data taken from game assets, game version 1.0. Listed values are without The Giver skill, which gives an extra 1-2 points.
All other characters will default to Neutral (+1).