What you get them as a gift.

Merlin-
You got Merlin a magic book that you found in the woods. You'd read the spells and knew they weren't a form of dark magic. Something from the Druids.

Arthur-
You get him a sword and a shield. The shield had the Camelot symbol on the front. On the back it said both your name and Arthur on it, both in equal writing. This symbols that you two were equals.

Mordred-
You got Mordred a book of magic that the Druids had made specifically for him. You helped in the making of the book of course.

What they get you as a gift

Merlin-
Merlin gets you a bundle of flowers and a love letter he wrote himself. Along with an adventure book.

Arthur-
Arthur got you flowers (he even picked them himself) and a knife. The knife was beautifully decorated with engraving of you names on the handle.

Mordred-
Mordred got you a Druid magic book. He wrote a spell on a piece of paper that would do whatever you commanded. Sadly, it only worked once a day.