An attempt for cleaning up the original image in a few steps.
Source Lazur URH
The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
This ons is quite old school looking. Retro, even. I like it.
Source Arno Declercq
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
From a drawing in 'Line and form', Walter Crane, 1914.
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 is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Clean and crisp lines all over the place. Wrap it up with this one.
Source Dax Kieran
Abstract Tiled Background Extended 12
Source GDJ
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Uses spirals from Pixabay. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
White handmade paper pattern with small bumps.
Source Marquis
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering