Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
This was formed by distorting an image of a background on Pixabay.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
A very slick dark rubber grip pattern, sort of like the grip on a camera.
Source Sinisha
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
Prismatic Abstract Background Design No Black
Source GDJ
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
"Beige Stone", Tileable Texture.
Source V. Hartikainen
Alternative colour scheme for the original floral pattern.
Source Firkin
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
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
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo