From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Feel free to download this "Dark Wood" background texture for your web site. The background tiles seamlessly!
Source V. Hartikainen
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
A seamlessly tile-able grunge background image.
Source V. Hartikainen
Fix and cc0 to get the tile this is based on.
Source SliverKnight