Colourful background #2007
 Colorful  CC 0

Made by distorting a simple pattern using the 'sin waves' plugin for Paint.net and vectorising in Vector Magic

Source Firkin

 More Textures
Retro Intro #893
 Gray  CC BY-SA 3.0

A slightly more textured pattern, medium gray. A bit like a potato sack?

Source Bilal Ketab

Straws #972
 Light  CC BY-SA 3.0

Super detailed 16×16 tile that forms a beautiful pattern of straws.

Source Pavel

Background pattern 214 (colour 5) #2374
 Green  CC 0

A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.

Source Firkin

Wood Old Panels #1435
 Wood  CC 0

Gamedev - Wood Textures. CC0 License.

Source Davit Masia

Background pattern [email protected] #562
 Dark  CC 0

Background pattern 104

Source Firkin

Paven #296
 Grid  CC BY-SA 3.0

A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.

Source Josh Green

Background pattern 312 #1860
 Blue  CC 0

Alternative colour scheme

Source Firkin

Background pattern 308 (colour 4) #1868
 Green  CC 0

Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.

Source Firkin

Paper 1 #15
 Paper  CC BY-SA 3.0

A slightly grainy paper pattern with small horizontal and vertical strokes.

Source Atle Mo

Prismatic Abstract Background Design No Black #404
 Noise  CC 0

Prismatic Abstract Background Design No Black

Source GDJ