Gun Metal #360
 Dark  CC BY-SA 3.0

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

Source Nikolay Boltachev

 More Textures
Geometric pattern #2004
 Grid  CC 0

A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i

Source Firkin

Textured Red Brown Plastic #878
 Wood  CC BY-SA 3.0

Textured Red Brown Plastic, Free Background Pattern. Although there's already enough plastic in our lives, let's bring it to the web too.)

Source V. Hartikainen

Prismatic Groovy Concentric Background No Black@2X #452
 Noise  CC 0

Prismatic Groovy Concentric Background No Black

Source GDJ

Background pattern purple #1946
 Colorful  CC 0

To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Prismatic Diamond Background 6 #383
 Diamond  CC 0

Prismatic Diamond Background 6

Source GDJ

Zodiac sign symbol background #1927
 Red  CC 0

Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern

Source Firkin