Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
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
A seamless texture of worn out "cardboard".
Source V. Hartikainen
A seamless pattern formed from a sports car on clker.com. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Polyskelion Pattern No Background
Source GDJ
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Here's a dark background pattern that contains a steel grid pattern as a texture. Use it as a website background or for other purposes. It's free!
Source V. Hartikainen
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
This one looks like a cork panel. Feel free to use it as a tiled background on your blog or website.
Source V. Hartikainen
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
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 seamlessly tile-able grunge background image.
Source V. Hartikainen
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.