Grows inside a mutated thornberry cactus in wet areas.
Use an Axe to harvest all the "Leaves" of the cactus, once all leaves are removed you will see brown looking pods on the inside, those are Thronberrys. You must get really close to harvest them(by hand).
Found inside the cactus plans located in green valley on medium maps
Thornberry cannot be crafted or recipe is not added yet