A bit like smudged paint or some sort of steel, here is scribble light.
Source Tegan Male
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
Prismatic Groovy Concentric Background 2
Source GDJ
Paper pattern with small dust particles and 45-degree strokes.
Source Atle Mo
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
Prismatic Groovy Concentric Background 4
Source GDJ
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
A free seamless background texture of "timber wall" (colored in dark brown).
Source V. Hartikainen
Prismatic Abstract Geometric Background 4
Source GDJ
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen