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
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
A cute x, if you need that sort of thing.
Source Juan Scrocchi
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Prismatic Chevrons Pattern 5 With Background
Source GDJ
This is a seamless pattern which is derived from a flower petal image.
Source Yamachem
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
A nice and simple white rotated tile pattern.
Source Another One
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen