A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Abstract Tiled Background Extended 6
Source GDJ
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
Abstract Ellipses Background Grayscale
Source GDJ
A nice and simple white rotated tile pattern.
Source Another One
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
Geometric triangles seem to be quite hot these days.
Source Pixeden
Background pattern originally a PNG drawn in Paint.net
Source Firkin
Remixed from an image on Pixabay uploaded by Prawny
Source Firkin