A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
Traced from a drawing in 'Household Stories from the Collection of the Brothers Grimm', Wilhelm Carl Grimm , 1882.
Source Firkin
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
Feel free to download and use it, or see the rest of the dark background patterns that I have made. Anyway, I hope you will find something that you like.
Source V. Hartikainen
A free background pattern with abstract green tiles.
Source V. Hartikainen
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
A seamless background texture of old cardboard.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using 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
The image depicts a seamless pattern of a Japanese family crest called "chidori" in Japanese .A chidori in Japanese means a plover in English.
Source Yamachem
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin