This can be planted to grow a mahogany tree. The Mahogany Seed is a seed that will grow into a Mahogany Tree in Stardew Valley. It can be obtained by shaking or chopping down Mahogany Trees ...

Remember to save hardwood for the Giant Stump Quest; plant Mahogany Seeds for extra help. Keep one of every fish for quests - especially important after completing the Giant Stump Quest.