Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
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
This texture looks like old leather. It should look great as a background on web pages.
Source V. Hartikainen
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Zero CC Mossy stone tileable texture, photographed and made by me. CC0
Source Sojan Janso
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks. https://cloaks.deviantart.com
Source Atle Mo
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
Formed by distorting an image on Pixabay that was uploaded by gustavorezende. To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
This is the remix of "plant pattern 02".I changed the object color to white and the BG to purple.The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:jp.pinterest.com/pin/500744052301423641/
Source Yamachem
It was called Navy Blue, but I made it dark. You know, the way I like it.
Source Ethan Hamilton
Looks like an old wall. I guess that’s it then?
Source Viahorizon
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
Prismatic Abstract Geometric Background 3
Source GDJ
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin