Number five from the same submitter, makes my job easy.
Source Dima Shiper
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
Remixed from a drawing in 'An Index to Deering's Nottinghamia Vetus et Nova', Rupert Chicken, 1899. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin
Vertical lines with a bumpy, yet crisp, feel to it.
Source Raasa
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
A seamless pattern formed from a square tile based on a jpg on Pixabay. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
A seamless background texture of old cardboard.
Source V. Hartikainen
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
A seamless pattern with a unit cell drawn as a bitmap in Paint.net and vectorized in Vector Magic.
Source Firkin
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen
Prismatic Abstract Background Design No Black
Source GDJ
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
Prismatic Abstract Geometric Background 4
Source GDJ
This is a hot one. Small, sharp and unique.
Source GraphicsWall
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning