Diamond pattern (colour 9) #2269
 Fabric  CC 0

From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.

Source Firkin

 More Textures
Prismatic Dots Background #501
 Noise  CC 0

Prismatic Dots 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

Inflicted #117
 Grid  CC BY-SA 3.0

Dark squares with some virus-looking dots in the grid.

Source Hugo Loning

Soft Wallpaper #95
 Wall  CC BY-SA 3.0

Coming in at 666x666px, this is an evil big pattern, but nice and soft at the same time.

Source Atle Mo

Leather 1 #13
 Light  CC BY-SA 3.0

A leather pattern with a hint of yellow.

Source Atle Mo

Background pattern 248 #2181
 Dark  CC 0

To get the tile this is made up from select the rectangle in Inkscape and use shift+alt+i.

Source Firkin

Prismatic Groovy Concentric Background 5@2X #466
 Dark  CC 0

Prismatic Groovy Concentric Background 5

Source GDJ

Lined Paper #362
 Stripes  CC BY-SA 3.0

The classic notebook paper with horizontal stripes.

Source Are Sundnes

Background pattern 15 #201
 Dark  CC 0

A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.

Source Firkin

Colorful Floral Background #479
 Noise  CC 0

Colorful Floral Background

Source GDJ

Fabric pattern (colour 3) #2400
 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

"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