This could be a hippy vintage wallpaper.
Source Tileable Patterns
The image depicts a seamless pattern of Japanese Edo pattern called "kikkou-matsu" or "亀甲松" meaning " tortoiseshell-pinetree".The real pinetree is like this: https://jp.pinterest.com/pin/500744052301065077/
Source Yamachem
Dark blue concrete wall with some small dust spots.
Source Atle Mo
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
The image depicts a seamless pattern of a tortoise in tortoiseshell (hexagon).
Source Yamachem
Prismatic Abstract Geometric Background 4
Source GDJ
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
Feel free to download and use it, or see the rest of the dark background patterns that I have made. Anyway, I hope you will find something that you like.
Source V. Hartikainen
Pixel by pixel, sharp and clean. Very light pattern with clear lines.
Source M.Ashok
Zero CC tileable ground (#2) cracked, crackled texture, made by me. CC0
Source Sojan Janso
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This one has rusty dark brown texture.
Source V. Hartikainen