Background pattern 215 #2371
 Brown  CC 0

A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.

Source Firkin

 More Textures
Stucco@2X #295
 Wall  CC BY-SA 3.0

A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.

Source Bartosz Kaszubowski

Blue Wallpaper For Websites #910
 Stripes  CC BY-SA 3.0

A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.

Source V. Hartikainen

Background pattern 309 (colour 4) #1863
 Green  CC 0

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

Source Firkin

Wood@2X #50
 Wood  CC BY-SA 3.0

Dark wooden pattern, given the subtle treatment. based on texture from Cloaks. https://cloaks.deviantart.com

Source Atle Mo

Rocky Wall@2X #42
 Light  CC BY-SA 3.0

High detail stone wall with minor cracks and specks.

Source Projecteightyfive

Seamless Wood Pattern #889
 Wood  CC BY-SA 3.0

A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.

Source V. Hartikainen

Retro Squares Background #414
 Noise  CC 0

Retro Squares Background

Source GDJ

Vintage tile background #2248
 Brown  CC 0

A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.

Source Firkin

Background pattern 4 #223
 Noise  CC 0

A pattern derived from repeating unit cells each derived from part of a mosaic in paint.net. The starting point for the mosaic was a picture of some prawns!

Source Firkin