Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Different from the original in being a simple tile stored as a pattern definition, rather than numerous repeated objects. Hence easy and quick to give this pattern to objects of different shapes. To get the tile in Inkscape, select the rectangle 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
Dark, crisp and subtle. Tiny black lines on top of some noise.
Source Wilmotte Bastien
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
More tactile goodness. This time in the form of some rough cloth.
Source Bartosz Kaszubowski
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
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
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Just like the black maze, only in light gray. Duh.
Source Peax
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert