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
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Same as Silver Scales, but in black. Turn your site into a dragon with this great scale pattern.
Source Alex Parker
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
This yellow background consists of a pattern of glossy gold buttons arranged in polka dot style on a seamless texture. Here's a pale yellow background pattern. Feel free to use it for your needs!
Source V. Hartikainen
From an image on opengameart.org shared by rubberduck.
Source Firkin
The tile can be had by selecting the rectangle in Inkscape and using shift+alt+i. Remixed from a drawing in 'Flowers of Song', Frederick Weatherly, 1895.
Source Firkin
Just like the black maze, only in light gray. Duh.
Source Peax
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Prismatic Abstract Geometric Background 4
Source GDJ
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
Alternative colour scheme. 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 mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
emixed from a JPG that was uploaded to Pixabay by Kyotime
Source Firkin
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
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
Light gray grunge wall with a nice texture overlay.
Source Adam Anlauf
Black brick wall pattern. Brick your site up!
Source Alex Parker
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado