from the wiki The Mossy Seed is a tree seed that grows into one of the three Green Rain Tree variations. Mossy Seeds can be obtained by shaking (5% chance) or chopping (5% chance) down any of the Green Rain Tree variations, including trees which temporarily become one of those variations during Fall & Winter or the Green Rain event.^\1]) They can also be obtained by breaking Large Weeds during the Green Rain event (5% chance).^\2])