A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
Textured Red Brown Plastic, Free Background Pattern. Although there's already enough plastic in our lives, let's bring it to the web too.)
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Formed by distorting an image on Pixabay that was uploaded by gustavorezende. To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Abstract Tiled Background Extended 10
Source GDJ
This one resembles a black concrete wall when is tiled. It should look great, at least with dark website themes.
Source V. Hartikainen
A cute x, if you need that sort of thing.
Source Juan Scrocchi
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Background formed from the original with an emboss effect
Source GDJ
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
The image is a design of blue glass.How about using it as background image?
Source Yamachem