Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
A browner version of the original weathered fence texture.
Source Firkin
Looks like an old rug or a computer chip.
Source Patutin Sergey
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
A dark metallic background with a pattern of stamped dots. Here's a dark "metallic" background pattern for you.
Source V. Hartikainen
A free light orange brown wallpaper with vertical stripes designed for use as a tiled background on websites. An yet another background pattern with vertical stripes.
Source V. Hartikainen
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein