Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
This ons is quite old school looking. Retro, even. I like it.
Source Arno Declercq
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
A dark metal plate with an embossed grid pattern and a bit of rust. Here's a dark metal plate texture for use as a tiled background on web pages.
Source V. Hartikainen
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
An orange vertically striped background pattern. Feel free to download and use this orange background pattern, for example, on the web). It resembles a wallpaper with vertical stripes or something similar to it.
Source V. Hartikainen
Black version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Black brick wall pattern. Brick your site up!
Source Alex Parker
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
A seamless pattern formed from a square tile based on a jpg on Pixabay. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin