Just to add to the excellent research performed by Anita. There were two couches that I am familiar with when it comes to Lincoln, both of which come much closer to reality in having anything to do with Lincoln.
The first, and likely most famous, is the so-called
Lincoln Courting Couch which Abraham and Mary sat on in the Edwards' home while developing their relationship. It was recently restored and rededicated at one of the Abraham Lincoln Association events. Looking at the picture, my guess is this is the couch you saw.
The second is the
couch in the Lincoln-Herndon Law office that Lincoln stretched out on while at work. It spent time in either the Jacksonville, Illinois office of former
U.S. Congressman Paul Findley or his Washington D.C. office, although i'm unsure where it is now. For all I know, Findley may still have it in his home in Jacksonville. For an interesting article on what Lincoln's purchase of the couch meant from a societal point of view, read
this.
Best
Rob
The Jefferson Lemen Compact - Was it True
