Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
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
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
The original enhanced with some gradients.
Source Firkin
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Just the symbols of the signs of the zodiac distributed in a chequer board-like pattern
Source Firkin
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A repeating background with dark brown stone-like texture and abstract pattern that looks like tree trunks.
Source V. Hartikainen
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee