Wavy background #2018
Colorful CC 0CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
More Textures
Background pattern 9 (B&W) #212
Dark CC 0Black & white version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Black Metal Pipes #1089
Metal CC BY-SA 3.0An abstract texture of black metal pipes (seamless).
Source V. Hartikainen
Geometric pattern 7 #1929
Dark CC 0To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dark Brown Timber Wall Texture #874
Wood CC BY-SA 3.0A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
Noise Pattern With Subtle Cross Lines #179
Grid CC BY-SA 3.0More bright luxury. This is a bit larger than fancy deboss, and with a bit more noise.
Source Viszt Péter
Zig-zag pattern 3 #2416
Grid CC 0A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Background pattern 238 (colour 2) #2228
Green CC 0To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Background pattern 254 #2144
Dark CC 0To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Background pattern 105@2X #564
Dark CC 0A seamless pattern formed from background pattern 102
Source Firkin
Background pattern 1 #220
Noise CC 0A pattern derived from repeating unit cells each derived from part of a fractal rendering in paint.net.
Source Firkin
"Dirty Paper", Seamless Background #1059
Paper CC BY-SA 3.0A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
Prismatic Abstract Line Art Pattern Background #565
Dark CC 0Prismatic Abstract Line Art Pattern Background
Source GDJ
Bamboo Background Pattern #1330
Green CC BY-SA 3.0This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
"Brown Stone Wall" #1026
Stone CC BY-SA 3.0A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Sine wave background #1735
Dark CC 0The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Background pattern blue #1940
Blue CC 0Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Background pattern 215 #2371
Brown CC 0A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Climpek #775
Grid CC BY-SA 3.0Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Light Striped Background #937
Stripes CC BY-SA 3.0A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
Rice Paper #338
Paper CC BY-SA 3.0Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo