If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
A large (588x375px) sand-colored pattern for your ever-growing collection. Shrink at will.
Source Alex Tapein
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
Black And White Floral Pattern Background from PDP.
Source GDJ
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Black And White Floral Pattern Background Inverse
Source GDJ
Clover with background for St. Patrick's Day. Add to a card with a doily, ribbon, a leprechaun or other embellishments.
Source BAJ
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
An abstract web texture of a polished blue stone (or does it look more like ice).
Source V. Hartikainen
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward