the entire inspiration for The Lord of the Rings was the Tolkien family preparing too much food for a feast day, and in the end gorging on that food so as to not waste it.
As Tolkien bitterly regretted this chain of events, the idea struck him: what if the world could be threatened by man's natural urge to not want to waste something that should have been thrown away?

In a personal failing he saw the template for a great tragedy, and then he wrote the rest of the book around it.