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
White little knobs, coming in at 10x10px. Sweet!
Source Amos
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
A pattern derived from part of a fractal rendering in Paint.net.
Source Firkin
This one is amazing, truly original. Go use it!
Source Viahorizon
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Sharp pixel pattern, just like the good old days.
Source Paridhi
ZeroCC tileable stone texture, edited from pixabay, CC0
Source Sojan Janso
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
It looks very nice I think.
Source V. Hartikainen
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
The original enhanced with some gradients.
Source Firkin
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers