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
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
A gray background pattern with a texture of textile. Suits perfectly for web design.
Source V. Hartikainen
The image depicts a Japanese Edo pattern called "kanoko or 鹿の子" meaning "fawn" which has a fur with small white spots.
Source Yamachem
This was submitted in a beige color, hence the name. Now it’s a gray paper pattern.
Source Konstantin Ivanov
A comeback for you: the popular Escheresque, now in black.
Source Patten
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
Sort of reminds me of those old house wallpapers.
Source Tish
Abstract Tiled Background Extended 6
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
The starting point for this was a texture drawn with the 'Radial Colors' plug-in in Paint.net.
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok