A comeback for you: the popular Escheresque, now in black.
Source Patten
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
Remixed from a JPG that was uploaded to Pixabay by Osckar
Source Firkin
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
A background pattern with blue on white vertical stripes.
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
Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
Here is a new seamless wood texture for using as blog or website backgrounds.
Source V. Hartikainen
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
This is a remix of "geometrical pattern 01".
Source Yamachem
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
I’m guessing this is related to the Sony Vaio? It’s a nice pattern no matter where it’s from.
Source Zigzain
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Geometric Pattern Background
Source GDJ
Abstract Tiled Background Extended 6
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo