Same classic 45-degree pattern, dark version.
Source Luke McDonald
The image is a design of blue glass.How about using it as background image?
Source Yamachem
Pattern formed from simple shapes. Black version.
Source Firkin
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Prismatic Groovy Concentric Background 5
Source GDJ
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
Prismatic Triangular Background Design Mark II 5
Source GDJ
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
It’s an egg, in the form of a pattern. This really is 2012.
Source Paul Phönixweiß
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Prismatic Curved Diamond Pattern No Background
Source GDJ