A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
A seamless pattern of "sewn stripes" colored in light gray.
Source V. Hartikainen
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
A white version of the very popular linen pattern.
Source Ant Ekşiler
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Fix and cc0 to get the tile this is based on.
Source SliverKnight
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
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Retro Circles Background 5 No Black
Source GDJ
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ