The Ring of Amity from Bigby Presents: Glory of the Giants has a property that states:
When you first attune to this ring, you can touch one willing creature and form a magical bond between the two of you. While this bond lasts, whenever you are subjected to a spell or magical effect that restores hit points, the bonded creature also receives the benefits of the spell or effect.
What happens if two player characters each attune a ring of amity, selecting each other as the bonded creature, and one of them pops a goodberry or drinks a potion of healing?