In D&D 5e, there are a lot of magic items. Some benefit more types of characters than others, and few benefit the Circle of the Moon Druid specifically. The ability to Wild Shape into beasts between rests can be formidable (especially when you get to do it twice), but the limitation on using magic items as a beast is not. I believe this class ability loses a little of it’s luster as the character rises in level, so I created a magic item specifically for such a character. In essence, it enhances the Wild Shape class ability.
Behold, the Necklet of the Moon, a magic item specifically created for the Moon Druid.
Rare / Necklace / Must Attune
This necklet gives a druid the ability to Wild Shape one additional time between rests. In addition, the druid may expend two uses of Wild Shape to change into a beast that is 1 CR higher than what they are normally allowed to change into. At level 20, the druid may always change into such a CR+1 beast.