While they can sometimes be unzipped and used as blankets, sleeping bags are not really something to decorate your room with. However, it's still house-wares related so...
Here is an interesting Sonic sleeping bag. They've created a somewhat game inspired night scene for him, with checkered ground, pattern water and some "Sonic 1" type hills, complete with full moon on the horizon. There are also pale 'line like' stars in the purple sky, but they are somewhat hard to see in the photo. The interior is not designed, and just solid color. This sleeping bag shares an unfortunate quality with others about the site that use this art: they have left off the white 'eye shines' on the Sonic stock-art, so it looks a little flat and dull. Still, a sleeping bag is a rather interesting Sonic item for your collection.