Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A free repetitive background with a dark concrete wall like texture. This one may be used in dark web site designs.
Source V. Hartikainen
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
Seamless Green Tile Background
Source V. Hartikainen
Prismatic Groovy Concentric Background 4
Source GDJ
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso
Tiny circle waves, almost like the ocean.
Source Sagive
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Zero CC tileable hard cover cells book texture, 4k, scanned and made by me. CC0
Source Sojan Janso
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
The name is totally random, but hey, it sounds good.
Source Atle Mo
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green