I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
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 green background pattern with warped vertical stripes and a grunge look.
Source V. Hartikainen
A heavy hitter at 400x400px, but lovely still.
Source Breezi
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Same classic 45-degree pattern, dark version.
Source Luke McDonald
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
From a drawing in 'Worsborough; its historical associations and rural attractions', Joseph Wilkinson, 1879.
Source Firkin
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 seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Derived from a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen
Uses spirals from Pixabay. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
A free pink background pattern.
Source V. Hartikainen
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić