Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
A nice one indeed, but I have a feeling we have it already? If you spot a copy, let me know on Twitter.
Source Graphiste
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Sweet and subtle white plaster with hints of noise and grunge.
Source Phil Maurer
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
Prismatic Geometric Pattern Background No Black
Source GDJ
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Polka Dots Mark II No Background
Source GDJ
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ