Background pattern 315 (colour 2) #1844
 Red  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

 More Textures
Triangular Psychosis 4 #236
 Noise  CC 0

A colorful triangular background, variation 4.

Source GDJ

Seamless Cardboard Texture #1212
 Cardboard  CC BY-SA 3.0

A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.

Source V. Hartikainen

Prismatic Isometric Cube Wireframe Pattern No Background #499
 Light  CC 0

Prismatic Isometric Cube Wireframe Pattern No Background

Source GDJ

Iron Grip #587
 Dark  CC BY-SA 3.0

Sounds like something from World of Warcraft. Has to be good.

Source Tony Kinard

Prismatic Abstract Line Art Pattern Background 2@2X #568
 Dark  CC 0

Prismatic Abstract Line Art Pattern Background 2

Source GDJ

Prismatic Floral Background #473
 Dark  CC 0

Prismatic Floral Background

Source GDJ

Background pattern 214 (colour 4) #2373
 Yellow  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

Prismatic Floral Background No Black@2X #476
 Light  CC 0

Prismatic Floral Background No Black

Source GDJ

Background pattern 207 #2466
 Yellow  CC 0

A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

"Green Rhombuses", Seamless Background Pattern #1336
 Green  CC BY-SA 3.0

A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.

Source V. Hartikainen