Heal Berries are quite common in Filgaia, they can be acquired as drop items from a large number of creatures (particularly in early levels).
In cities and villages they can be found in boxes and chests, or they can be bought in the houses of comrades.
Wild Arms: Recovers 200 HP to one target.
Wild Arms 2: Recovers 500 HP to one target.
Wild Arms 3: Recovers 300 HP to one target.
Mariel has a skill named after the berry, which mirrors it's effects healing the person by restoring 100hp.