Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Prismatic Hypnotic Pattern No Background
Source GDJ
Here's a camo print with more tan and less green, such as might be used in a desert scenario. This is tileable, so it can be used as a wallpaper or background.
Source Eady
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
Light and tiny, just the way you like it.
Source Rohit Arun Rao
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Subtle scratches on a light gray background.
Source Andrey Ovcharov