Retro Squares Background 4 #418
 Dark  CC 0

Retro Squares Background 4

Source GDJ

 More Textures
"Black Chains", Gloomy Background #1082
 Metal  CC BY-SA 3.0

A repeating gloomy background image. This one consists of a pattern of black chains layered on top of a dark textured background.

Source V. Hartikainen

Fabric pattern (colour 4) #2399
 Fabric  CC 0

Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

Little Knobs@2X #311
 Light  CC BY-SA 3.0

White little knobs, coming in at 10x10px. Sweet!

Source Amos

Background pattern 315 #1845
 Blue  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

Vintage pattern #1961
 Grid  CC 0

Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.

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

Black Mamba #57
 Dark  CC BY-SA 3.0

The name alone is awesome, but so is this sweet dark pattern.

Source Federica Pelzel

Robots #125
 Dark  CC BY-SA 3.0

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

Source Seamless Studio

Prismatic Geometric Pattern Background 2 #409
 Noise  CC 0

Prismatic Geometric Pattern Background 2

Source GDJ