Stricktly speaking, this image shouldn't be here, for the symmetry pattern in it was intentionally placed, by someone well aware of the 17 wallpaper groups. But it is here anyway, because:

1. It came up in an everyday place, a fabric store. (Thanks for spotting it, Dylan!)
2. 3*3 patterns are really rare.
3. Through a web search for the keywords at the bottom of the image, I was delighted to find that an established quilter had written a highly praised book about quilting and tesselations.