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
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
You guessed it – looks a bit like cloth.
Source Peax Webdesign
Heavily remixed from a drawing in 'Barbara Leybourne; a story of eighty years ago', Sarah Hamer, 1889.
Source Firkin
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. A version of the original with random colors.
Source Firkin
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Colour version of the original pattern inspired by the front cover of 'Old and New Paris', Henry Edwards, 1894.
Source Firkin
This one needs to be used in small areas; you can see it repeat.
Source Luca
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
To celebrate the new feature, we need some sparkling diamonds.
Source Atle Mo
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß