Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
Tiny circle waves, almost like the ocean.
Source Sagive
Seamless Dark Grunge Texture. Here's a new grunge texture for use as a background.
Source V. Hartikainen
Sharp but soft triangles in light shades of gray.
Source Pixeden
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Prismatic Hexagonalist Pattern No Background
Source GDJ
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Looks as if it's spray painted on the wall. You can be sure that this pattern will seamlessly fill your backgrounds on web pages.
Source V. Hartikainen
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
First pattern tailor-made for Retina, with many more to come. All the old ones are upscaled, in case you want to re-download.
Source Atle Mo
A bit of scratched up grayness. Always good.
Source Dmitry
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
A dark metallic background with a pattern of stamped dots. Here's a dark "metallic" background pattern for you.
Source V. Hartikainen
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin