As far as I can tell, no *named* plant species are stated as native (uniquely or non-uniquely) to the Feywild in *5th Edition* material. But, we have an example of a plant that is unique to the Feywild, though its name is not given. 

In *Ghosts of Saltmarsh*, there is a hull upgrade available to ships called [*Living Vessel*](https://www.dndbeyond.com/sources/gos/of-ships-and-the-sea#LivingVessel):

>This vessel’s hull was crafted in the Feywild under the direction of master eladrin shipwrights. It is a living plant, drawing sustenance from water and sunlight. Vines covered in thick leaves hang over its side, and the wood runs with fresh sap when damaged. The ship gains a +2 bonus to all Constitution checks or saving throws. As long as the ship has at least 1 hit point, it regains 10 hit points every minute.

The *ship itself* is a plant that is native to the Feywild, so whatever plant this ship upgrade is made from is an example of what you're looking for.