Hani
Tiller
It would be like a sort of "legendary crop" rarer than the ancient seed, and you would have to plant it on the first week of spring to make sure it has time to grow before the next winter starts or it wouldn't survive and finish growing. Once successfully grown it would work as some sort of ladder vine you can climb on to access a new area in the game, and remain available forever. some kind of dungeon where you can farm resources, inspired by Jack and the Beanstalk.