Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
This seamless web background texture looks like gray stone. It's great for using as a background image on web pages, or on some of their elements. Anyway, I hope you will find use for it.
Source V. Hartikainen
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
Number 5 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic
Source Firkin
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Pattern produced in Paint.net using the Vibrato plug-in.
Source Firkin
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
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Prismatic Geometric Pattern Background
Source GDJ
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
A seamlessly tile-able grunge background image.
Source V. Hartikainen
Abstract Tiled Background Extended 10
Source GDJ
A version without colours blended together to give a different look.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This one could be the shirt of a golf player. Angled lines in different thicknesses.
Source Olivier Pineda
A free seamless texture of reptile skin colored in a dark brown color. As always, you may use it as a repeated background image in your web design works, or for any other purposes.
Source V. Hartikainen
To celebrate the new feature, we need some sparkling diamonds.
Source Atle Mo
Retro Circles Background 8 No Black
Source GDJ