From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
From a drawing in 'Hundert Jahre in Wort und Bild', S. Stefan, 1899.
Source Firkin
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
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
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
Zero CC bark from fur tree tileable texture, photographed and made by me. CC0
Source Sojan Janso
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
A pattern derived from part of a fractal rendering in Paint.net.
Source Firkin
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
A version without colours blended together to give a different look.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A version without colours blended together to give a different look.
Source Firkin