A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857
Source Firkin
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Prismatic Hexagonalist Pattern No Background
Source GDJ
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
An attempt for cleaning up the original image in a few steps.
Source Lazur URH
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
Pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
A version without colours blended together to give a different look.
Source Firkin
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Oh yes, it happened! A pattern in full color.
Source Atle Mo
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Prismatic Abstract Background Design
Source GDJ