Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
Classic vertical lines, in all its subtlety.
Source Cody L
So tiny, just 7 by 7 pixels – but still so sexy. Ah yes.
Source Dmitriy Prodchenko
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
Abstract Ellipses Background Grayscale
Source GDJ
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by Osckar
Source Firkin
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
From drawing in 'Musings in Maoriland', Thomas Bracken, 1890.
Source Firkin
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
Prismatic Chevrons Pattern 5 With Background
Source GDJ
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber