Pillows are the vane of my life, I have several inflatable types that I hate and I can't get on with stuffing clothes into a stuff sac so I had an idea and tried it out last weekend and it really worked a treat for me...
Take a new synthetic filled pillow (can buy them for £3) and cut it in half width-wise and stitch the cut edges of the outer fabric so that you end up with two half width pillows.
The half width fits a sleeping bag a treat.
Put one or both halves (depending on how high you like your pillows) into one of those 'vacuum bags' that you can expel the Air from by rolling it up and hey presto... you've got a compressed pillow arrangement that will fit into your rucksack.