Here's a dark background pattern that contains a steel grid pattern as a texture. Use it as a website background or for other purposes. It's free!
Source V. Hartikainen
White circles connecting on a light gray background.
Source Mark Collins
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
The image a seamless pattern of a wire-mesh fence.I want you to use this pattern as a lower layer.
Source Yamachem
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Sharp but soft triangles in light shades of gray.
Source Pixeden
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
A version without colours blended together to give a different look.
Source Firkin
Prismatic Abstract Geometric Background 5
Source GDJ
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo