Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Remixed from a drawing in 'Kulturgeschichte der Deutschen im Mittelalter' Franz von Loeher, 1891. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Remixed from a drawing in 'Canadian forest industries July-December', 1915
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Tile available in Inkscape using shift-alt-i on the selected rectangle
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Black brick wall pattern. Brick your site up!
Source Alex Parker