In this tutorial J.Y.Amihud has shown us a very easy and smart way to create pillows in Blender. First we have to take a box or cube mesh in blender or you can create a plane then extrude the faces to give it a thickness.
Then you have to add subdivisions as you need them afterwards. So go to the edit mode then right click and select "subdivision" and put the number of cuts you required. Then go to the dynamics or physics section ans make it a cloth surface and turn on the self collision. Increase the distance value to around " .8 " or according to the requirement of the scene. then play the simulation and you can see the cloth object was making a pillow like shape. play the timeline manually by scrubbing the timeline. When you are happy with the shape then apply the cloth and make it a poly object from the settings.
Now you can add smooth to this object to give it a final touch. Follow the tutorial for the details its very basic and also easy to create.