A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
An abstract Background pattern of purple twisty patterns.
Source TikiGiki
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
A free black metallic background pattern. Here's a new pattern I made that looks metallic.
Source V. Hartikainen
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
A seamless pattern formed from a tile made from ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Light and tiny, just the way you like it.
Source Rohit Arun Rao
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A dark background pattern/texture of a dimpled metal plate.
Source V. Hartikainen
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Dead simple but beautiful horizontal line pattern.
Source Fabian Schultz
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
Mostly just mucked about with the colours and made one of the paths in the lead frame opaque. The glass remains transparent.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
ZeroCC tileable wood boards texture, photographed and made by me. CC0
Source Sojan Janso
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin