Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
A comeback for you: the popular Escheresque, now in black.
Source Patten
This background pattern contains a texture of yellow wood planks. I think it looks quite original.
Source V. Hartikainen
A seamlessly tileable pink background texture.
Source V. Hartikainen
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
Fake or not, it’s quite luxurious.
Source Factorio.us Collective