If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Can’t believe we don’t have this in the collection already! Slick woven pattern with crisp details.
Source Max Rudberg
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Alternative colour scheme for the original floral pattern.
Source Firkin
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
One more updated pattern. Not really carbon fiber, but it’s the most popular pattern, so I’ll give you an extra choice.
Source Atle Mo
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:https://jp.pinterest.com/pin/500744052301423641/
Source Yamachem
This light background pattern has a texture of "frozen" surface with diagonal stripes. Here's an yet another addition to the collection of free website backgrounds.
Source V. Hartikainen
Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8