Leaf Stone Ore
From Pixelmon Wiki
Leaf Stone ore is an ore that drops a single Leaf Stone shard when mined with a pickaxe. When nine shards are obtained, they can be crafted into a Leaf Stone.
Leaf Stone ore can be found in all variants of forest and taiga biomes. The ore only spawns directly under leaves and within stone, causing it to be located underground but very close to the surface.