Old Mathematics@2X #44
 Stripes  CC BY-SA 3.0

This one takes you back to math class. Classic mathematic board underlay.

Source Josh Green

 More Textures
Micro Carbon@2X #8
 Carbon  CC BY-SA 3.0

Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.

Source Atle Mo

Decorative divider 230 #2150
 Dark  CC 0

From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.

Source Firkin

Concrete Wall 3 #93
 Light  CC BY-SA 3.0

All good things come in threes, so I give you the third in my little concrete wall series.

Source Atle Mo

Gun Metal@2X #361
 Dark  CC BY-SA 3.0

With a name this awesome, how can I go wrong?

Source Nikolay Boltachev

Prismatic Dots Background 4 #507
 Noise  CC 0

Prismatic Dots Background 4

Source GDJ

Background pattern 104 #561
 Dark  CC 0

Background pattern 104

Source Firkin

Prismatic Dots Background 2@2X #504
 Noise  CC 0

Prismatic Dots Background 2

Source GDJ

Prismatic Groovy Concentric Background No Black #451
 Noise  CC 0

Prismatic Groovy Concentric Background No Black

Source GDJ

Always Grey@2X #54
 Dark  CC BY-SA 3.0

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

Source Stefan Aleksić