People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
A seamless texture of a rough concrete surface.
Source V. Hartikainen
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
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
Prismatic Hypnotic Pattern No Background
Source GDJ
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
From a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
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
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
Inspired by a design found in 'Konstantinápolyi emlékeim', Miklos Chriszto, 1893.
Source Firkin
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
Floral patterns will never go out of style, so enjoy this one.
Source Lasma
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
From a drawing of the coat of arms of the Ottoman Empire on Wikimedia.
Source Firkin
Background formed from the original with an emboss effect
Source GDJ
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim