People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
This one is amazing, truly original. Go use it!
Source Viahorizon
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
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
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
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
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Remixed from a PNG that was uploaded to Pixabay by gingertea
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Bigger is better, right? So here you have some large carbon fiber.
Source Factorio.us Collective
Pattern formed from simple shapes. Black version.
Source Firkin
The tile can be had by using shift+alt+i on the selected rectangle in Inkscape
Source Firkin