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
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Inspired by a design found in 'Konstantinápolyi emlékeim', Miklos Chriszto, 1893.
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
The tile can be had by selecting the rectangle in Inkscape and using shift+alt+i. Remixed from a drawing in 'Flowers of Song', Frederick Weatherly, 1895.
Source Firkin
A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
An abstract texture of black metal pipes (seamless).
Source V. Hartikainen
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Someone was asking about how to achieve a fur pattern at #inkscape irc so tried to make a filter on it. Flood filled fractal noises rigged together. May someone find a good use for these.
Source Lazur URH
The original enhanced with some gradients.
Source Firkin
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin