Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
Sharp diamond pattern. A small 24x18px tile.
Source Tom Neal
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A smooth mid-tone gray, or low contrast if you will, linen pattern.
Source Jordan Pittman
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
Prismatic Groovy Concentric Background 2 No Black
Source GDJ