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 image depicts a seamless pattern of Japanese Edo pattern called "kikkou-matsu" or "亀甲松" meaning " tortoiseshell-pinetree".The real pinetree is like this: https://jp.pinterest.com/pin/500744052301065077/
Source Yamachem
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
Remixed from a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
A free background pattern with abstract green tiles.
Source V. Hartikainen
A repeating graphic with ancient pattern. I came up with this name/title at last minute, so you may find that there is very little of ancientness in this pattern after all.
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
A version without colours blended together to give a different look.
Source Firkin
Alternative colour scheme for the original floral pattern.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin