I have a single chair and don't know the value of it since it is not with a set. Stamped on the bottom with "Murphy Chair Company, Detroit, MI, No 354".
I found this website: https://www.justcollecting.com/furniture/murphy-chair-company-furniture that says the company was formed in 1872 and moved from Detroit in 1919 so it has to be in that date range. The chair is in very sturdy condition, but is a bit marked up.
I can send better quality photos if needed.
Any help would be appreciated!