Chop Large Stumps with a Copper Axe or better
Chop Large Logs with a Steel Axe or better
Break Mahogany Trees for hardwood
Clear the Secret Woods daily for hardwood from Large Stumps
Farm the Farm Cave if it has hardwood sources in mods or special setups
Choose the Lumberjack profession for more wood drops, helping access hardwood sources faster
Open Hardwood from the Traveling Cart when available
Get hardwood from the Desert Trader by exchanging resources
Use the Woodskip Fish Pond for hardwood as a possible reward
Check the Quarry Mine and other special areas for hardwood sources in certain game states
Recycle hardwood-related items only if a mod or special source provides them