You may use it as is, or modify it as you like.
Source V. Hartikainen
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Abstract Background Design No Black
Source GDJ
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
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
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
Remixed from a raster on Pixabay, that was uploaded by ArtsyBee.
Source Firkin
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Sharp pixel pattern, just like the good old days.
Source Paridhi
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
"Beige Stone", Tileable Texture.
Source V. Hartikainen
Colour version of the original seamless pattern.
Source Firkin