You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Original seamless pattern with an Inkscape filter.
Source Firkin
Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
Zero CC tileable dry grass texture, photographed and made by me. CC0
Source Sojan Janso
A seamlessly tileable pink background texture.
Source V. Hartikainen
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Derived from a JPG that was uploaded to Pixabay by ractapopulous
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Sort of like the back of a wooden board. Light, subtle, and stylish, just the way we like it!
Source Nikolalek
Some dark 45 degree angles creating a nice pattern. Huge.
Source Dark Sharp Edges
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Seamless Prismatic Quadrilateral Line Art Pattern No Background
Source GDJ
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf