A seamless texture of worn out "cardboard".
Source V. Hartikainen
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
One more from Badhon, sharp horizontal lines making an embossed paper feeling.
Source Badhon Ebrahim
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Tiny circle waves, almost like the ocean.
Source Sagive
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
To get the tile this is based on, 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
This is a seamless pattern which is derived from a flower petal image.
Source Yamachem
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous