From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
The tile this is based on was adapted from an image that was uploaded to Pixabay by frolicsomepl. It can be had in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Remixed 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
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
White little knobs, coming in at 10x10px. Sweet!
Source Amos
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Feel free to download and use it, or see the rest of the dark background patterns that I have made. Anyway, I hope you will find something that you like.
Source V. Hartikainen
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso