It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Tile available in Inkscape using shift-alt-i on the selected rectangle
Source Firkin
A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
This was formed by distorting an image of a background on Pixabay.
Source Firkin
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
Just like the black maze, only in light gray. Duh.
Source Peax
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
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