A comeback for you: the popular Escheresque, now in black.
Source Patten
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Greyscale version of a pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
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
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Inspired by the B&O Play, I had to make this pattern.
Source Atle Mo
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless pattern of "sewn stripes" colored in light gray.
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
A seamless background texture of old cardboard.
Source V. Hartikainen
A classic dark tile for a bit of vintage darkness.
Source Listvetra
There are many carbon patterns, but this one is tiny.
Source Designova
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Abstract Tiled Background Extended 10
Source GDJ
Prismatic Rounded Squares Grid 3 No Background
Source GDJ