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 drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
A repeating background with wood/straw like texture.
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
The texture of this background image has some similarities with leather, and it's colored in a dark brown color. So, if you are looking for a dark brown background image for your website, this may be an option for you.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A seamless pattern based on a tile that can be achieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
I love the movie Pineapple Express, and I’m also liking this Pineapple right here.
Source Audee Mirza
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
Remixed from an image that was uploaded to Pixabay by KirstenStar
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos