Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Colour version of the original pattern.
Source Firkin
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
An interesting dark spotted pattern at an angle.
Source Hendrik Lammers
Prismatic Groovy Concentric Background 3
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
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
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
Medium gray pattern with small strokes to give a weave effect.
Source Catherine
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
A bit strange this one, but nice at the same time.
Source Diogo Silva
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Floral patterns will never go out of style, so enjoy this one.
Source Lasma