Always Grey #53
 Dark  CC BY-SA 3.0

Crossing lines with a subtle emboss effect on a dark background.

Source Stefan Aleksić

 More Textures
Robots@2X #126
 Dark  CC BY-SA 3.0

And some more testing, this time with Seamless Studio. It’s Robots FFS!

Source Seamless Studio

Grunge Wall@2X #82
 Wall  CC BY-SA 3.0

Light gray grunge wall with a nice texture overlay.

Source Adam Anlauf

3px Tile@2X #343
 Dark  CC BY-SA 3.0

Tiny dark square tiles with varied color tones.

Source Gre3g

Background pattern 272 (colour 2) #2056
 Pink  CC 0

A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Rocky Wall #41
 Wall  CC BY-SA 3.0

High detail stone wall with minor cracks and specks.

Source Projecteightyfive

Lined Paper@2X #363
 Stripes  CC BY-SA 3.0

The classic notebook paper with horizontal stripes.

Source Are Sundnes

Dark Circles #306
 Dark  CC BY-SA 3.0

People seem to enjoy dark patterns, so here is one with some circles.

Source Atle Mo

Background pattern 315 (colour 4) #1842
 Colorful  CC 0

The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i

Source Firkin

Background pattern 266 #2068
 Dark  CC 0

Remixed from a drawing in 'Some account of the Worshipful Company of Ironmongers', John Nicholl, 1866.

Source Firkin