Pearl of Power

The pearl of power is a magical item that allows a spellcaster to regain one expended spell slot of 3rd-level or lower once per dawn.

Description
"While this pearl is on your person, you can use an action to speak its command word and regain one expended spell slot. If the expended slot was of 4th level or higher, the new slot is 3rd level. Once you use the pearl, it can't be used again until the next dawn."

The Campaign of Vox Machina
First seen in the first campaign as an item for sale at Gilmore's Glorious Goods, the pearl came under the possession of Vex'ahlia de Rolo. As a ranger, it proved to be a worthwhile asset to her otherwise smaller pool of spell slots.

Campaign Two: The Mighty Nein
Another pearl of power was found in The Invulnerable Vagrant, under the ownership of Enchanter Pumat Sol. It was purchased by Jester Lavorre.

Owners

 * Shaun Gilmore and Pumat Sol (vendors)
 * Vex'ahlia de Rolo
 * Jester Lavorre

Trivia

 * Both pearls of power seen in the campaign have been purchased and subsequently used by characters played by Laura Bailey.