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
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Classic 45-degree pattern, light version.
Source Luke McDonald
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Medium gray pattern with small strokes to give a weave effect.
Source Catherine
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Same as the black version, but now in shades of gray. Very subtle and fine grained.
Source Atle Mo
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua