Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
From a drawing in 'Real Sailor-Songs', John Ashton, 1891.
Source Firkin
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
Adapted from an image that was uploaded to Pixabay by Anerma.
Source Firkin
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Abstract Geometric Background 4
Source GDJ
From a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Green Web Background, Seamless tile.
Source V. Hartikainen
Prismatic Geometric Pattern Background 2
Source GDJ
Remixed from a JPG that was uploaded to Pixabay by Osckar
Source Firkin
This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin