Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
An alternative colour scheme for the original seamless texture formed from an image on Pixabay.
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Hexagonal dark 3D pattern. What more can you ask for?
Source Norbert Levajsics
I scanned a paper coffee cup. You know, in case you need it.
Source Atle Mo
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
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
Redrawn based on a drawing in 'По Сѣверо-Западу Россіи' Konstantin Sluchevsky, 1897.
Source Firkin
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen
A seamless pattern formed from a modified version of rwwgub's tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ