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
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
Prismatic Polyskelion Pattern No Background
Source GDJ
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
Uses spirals from Pixabay. To get the basic tile select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
Background pattern originally a PNG drawn in Paint.net
Source Firkin
A seamless pattern formed from miutopia's cakes on a tablecloth.
Source Firkin
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
Here is a new seamless wood texture for using as blog or website backgrounds.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Tiny, tiny 3D cubes. Reminds me of the good old pattern from k10k.
Source Etienne Rallion
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen
To get the tile this is based on, 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