In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
A seamless canvas texture for using as background on websites. Colored in pale tones of brown.
Source V. Hartikainen
Thin lines, noise and texture creates this crisp dark denim pattern.
Source Marco Slooten
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
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
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski