Herebelow are 3 magic items from the 3.0/3.5 DMG, converted to 5e:

Potion of Barkskin

Potion, uncommon

When you drink this potion, you gain the effect of the Barkskin spell for 1 hour (no concentration required) or until you end the effect as a bonus action. This potion’s liquid looks like stagnant water with pieces of bark floating. When ingested, the bark dissolves as it exits the potion.

Wand of Mage Armor

Wand, uncommon

This wand has 15 non-rechargeable charges. While holding it, you can use an action to expend 1 of its charges to cast the Mage Armor spell from it.

Once all the charges have been expended, the wand crumbles into ashes and is destroyed.

Elemental Gem

Wondrous item, rare

This gem contains a conjuration spell attuned to a specific Elemental Plane (Air, Earth, Fire or Water). When the gem is crushed, smashed, or broken (as a standard action), an elemental appears within 10ft. The elemental is under the control of the creature that broke the gem for 1 minute and will disappear after that. Controlling the elemental require giving direction similar to a ranger’s companion: the elemental will move where commanded (no action required to command), or Attack, Dash, Disengage, Dodge or Help at the expense of an action from the commanding creature, to be verbally instructed.

The coloration of the gem varies with the type of elemental it summons. Air elemental gems are transparent, earth elemental gems are light brown, fire elemental gems are reddish orange, and water elemental gems are blue-green.