Make a circle on the ground plane to use as a pathfor follow me, and a vertical circle to use as a profilefor the button:
Capture.JPG
Draw a horizontal line just under the center of profilecircle, and erase the bottom arc. Scale the profileshape along the blue axis to get the cross section of a button.
Capture2.JPG
Select the path, then click on the profilewith the follow me tool, like so:
Capture3.JPG
If you need a plugin for making the cushion, that's probably the Subdivide and Smooth (or Artisan) plugin...search the "Tutorials" forum for "sofa"...