A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A browner version of the original weathered fence texture.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
A free pink background pattern.
Source V. Hartikainen
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
I’m starting to think I have a concrete wall fetish.
Source Atle Mo
Green Web Background, Seamless tile.
Source V. Hartikainen
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin