ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
A repeatable image with dark background and metal grid pattern.
Source V. Hartikainen
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
A seamless pattern of "sewn stripes" colored in light gray.
Source V. Hartikainen
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
8 by 8 pixels, and just what the title says.
Source pixilated
An aged paper background tile with smeared and pressed text.
Source V. Hartikainen
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
Source Firkin
Colorful Floral Background No Black
Source GDJ
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
A light gray background pattern with seamless fabric-like texture and almost unnoticeable stripes.
Source V. Hartikainen
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
An alternative colour scheme for the original background.
Source Firkin
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ