A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
A seamless texture of worn out "cardboard".
Source V. Hartikainen
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868.
Source Firkin
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A beautiful dark padded pattern, like an old classic sofa.
Source Chris Baldie
Inspired by an image that was uploaded to Pixabay by geralt
Source Firkin
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Looks like an old wall. I guess that’s it then?
Source Viahorizon
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
Prismatic Geometric Pattern Background
Source GDJ
Here's a quite bright pink background pattern for use on websites. It doesn't look like a real fur, but it definitely resembles one.
Source V. Hartikainen