An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Prismatic Abstract Background Design No Black
Source GDJ
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
A light background pattern with diagonal stripes. Here's a simple light striped background for you.
Source V. Hartikainen
Tiny circle waves, almost like the ocean.
Source Sagive
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from a drawing in 'The Canadian horticulturist', 1892
Source Firkin
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Background pattern made in "Grunge-Like" style. Available in both SVG and JPG formats. Edit to your needs then click the download button.
Source V. Hartikainen
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
A seamless pattern based on a tile that can be achieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin