I have a fairly elaborate headcanon for what sort of wood each of the Ten Thrones depicted in this mod is made out of. As with many details in this mod, it is not strictly canonical (we do not have these details), but it is canon-inspired, attempting to capture the culture and aesthetic of each Kingdom in some way. I usually restrict myself to inflicting this sort of excessive elf worldbuilding on my closest friends, but one of them felt that you, dear reader, might be enriched by understanding the intended meaning behind the Thrones' designs.

So, here is a short summary of my thoughts on Elf Chairs:

Ten Thrones Art (click to reference)

• Avelorn
  A honey-hued oak. A beautiful tree, the oak is also one of the most long-lived, and its prolific acorns invoke fertility, making it the perfect symbol for Isha's chosen matriarchy.
  
• Caledor
  Sandalwood, a tree that would thrive in Caledor's volcanic soil, and an expensive wood considered to have mystical properties that Caledor's famous mages would prize.
  
• Chrace
  A hardy hickory, tough as a Chracian.
  
• Cothique
  A pale, washed-out plank of starwood, meant to look like reclaimed driftwood from the sea. Inscribed with the elven rune "Hadri," representing ships and the endless voyage.
  
• Eataine
  Mahogany, a regal and expensive choice for the noble heartland of Ulthuan, and neither particularly bright nor dark.
  
• Ellyrion
  Naturally, Ellyrion's famous nightelm wood was selected. Resistant to dark magic, the groves of this tree were burned to the ground by Malekith, but the throne of Ellyrion's Prince(ss) would surely be made of such a material, both for regional pride and to protect against assassination. The back of the chair is marked with the mandala of Kurnous I designed for Alshua's Ellyrion.
  
• Nagarythe
  Black walnut, both for the dark aesthetic and the durability and resistance to decay exhibited by those elves who resisted Malekith's corruption. The headboard is absent for the same reason Nagarythe's nobles often cover their heraldry.
  
• Saphery
  The mystically associated ebony, a dense wood suitable for items where precision and consistency is vital, such as musical instruments and, one presumes, magical items. Has extra gemstones and a filigreed mandala of the god of wisdom, Hoeth.
  
• Tiranoc
  A bright golden ashwood. Its color flatters Tiranoc's sunrise heraldry, and the wood type is strong but light, suitable for the construction of chariots.
  
• Yvresse
  A stately, dark walnut. Tough, but faded, just like Yvresse.