The description of the Goodberry spell states:
Up to ten berries appear in your hand and are infused
with magic for the duration. A creature can use its
action to eat one berry.
According to the Wikipedia article on Watermelons:
It is grown for its edible fruit, also known as a watermelon, which is a special kind of berry botanically called a pepo.
Emphasis mine. Given these two bits of information, can the Goodberry spell be used to summon ten watermelons, which can then each be eaten as a standard action?
Best Answer
No, nothing in the spell gives the caster choices about the berries. They're just archetypal berries (because that's what a category word like “berry” means when it's otherwise not specified), so they're small round fruits that fit in your hand, as implied by the spell's wording about them all appearing in your hand.