Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Pattern Background
Source GDJ
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
You know you love wood patterns, so here’s one more.
Source Richard Tabor
Dark blue concrete wall with some small dust spots.
Source Atle Mo
The image depicts a seamless pattern which includes hexagonally-aligned gourds with BG in light-brown.
Source Yamachem
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
ZeroCC tileable beechwood wood texture, generated in Neo Texture Edit by me. CC0
Source Sojan Janso
Background pattern made in "Grunge-Like" style. Available in both SVG and JPG formats. Edit to your needs then click the download button.
Source V. Hartikainen
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Looks as if it's spray painted on the wall. You can be sure that this pattern will seamlessly fill your backgrounds on web pages.
Source V. Hartikainen