To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i
Source Firkin
Free tiled background with colorful stripes and white splatter.
Source V. Hartikainen
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Derived from an image that was uploaded to Pixabay by TheDigitalArtist
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
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
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Sharp pixel pattern looking like some sort of fabric.
Source Dmitry
This tiled background comes in red and consists of tiles that look like gemstones. It is more for blogs or social profiles, I think.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by darkmoon1968
Source Firkin
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
You were craving more leather, so I whipped this up by scanning a leather jacket.
Source Atle Mo
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
A free background pattern with abstract green tiles.
Source V. Hartikainen
I’m not going to lie – if you submit something with the words Norwegian and Rose in it, it’s likely I’ll publish it.
Source Fredrik Scheide
A cute x, if you need that sort of thing.
Source Juan Scrocchi