I like my head elevated a bit higher, and have, over the years, tried everything from
1. using the small Slumberjack qualofill pillows,
2. using one of my MSR Dromedary bags filled with either air or water,
3. Using a Camelback style bag filled with air or water,
4. using my stuff sack inside out filled with Clothes
(I have one like Dory's, lined with a soft material used inside out).
I found I didn't care for the first three.
The fourth is nice, However, there are times when as Pete says, you have all your clothes on and don't really have anything to use. It was in a situation similar to this that I ended up taking my nylon first aid kit, my nylon emergency essential kit, Plastic toilet paper baggie (Clean Plastic Toilet paper baggie that is ), and stuffing them into a spare stuff sack that I always carry. I then stuffed this into the very bottom of my pack along with the foam mesh backpad part of my pack that is velcroed to the pack, and laid the pack cross-ways at the head of my tent. I then place my foam sitpad on the pack and found it worked out well - I get about 4"-6" of "pillow". The backpack doesn't slide around and the foam sitpad and foam backpad offer a protection from the lumpiness of the "Fill" Materials.
The other thing I do is always carry a spare soft nylon balaclava in my sleeping bag pocket. I have put it over a smaller stuff sack filled with socks, bandannas & toilet paper and then placed it on my pack (which is laid lengthwise at the head of the tent). The pack gives a nice 2" rise and then the soft stuff sack is another 2"-3". The balaclava keeps it soft and keeps it from slipping on the backpack cordura fabric.