Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
Medium gray fabric pattern with 45-degree lines going across.
Source Atle Mo
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
Prismatic Snowflakes Pattern 2 No Background
Source GDJ
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
Derived from a drawing in 'Elfrica. An historical romance of the twelfth century', Charlotte Boger, 1885
Source Firkin
This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen
New paper pattern with a slightly organic feel to it, using some thin threads.
Source Atle Mo
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin