A version without colours blended together to give a different look.
Source Firkin
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Medium gray pattern with small strokes to give a weave effect.
Source Catherine
Prismatic Snowflakes Pattern No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Prismatic Groovy Concentric Background 4
Source GDJ
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
Non-seamless pattern drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
Might not be super subtle, but quite original in its form.
Source Alex Smith
Prismatic Abstract Line Art Pattern Background
Source GDJ
From a drawing in 'Az Osztrák-Magyar Monarchia irásban és képben', 1885.
Source Firkin
The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:https://jp.pinterest.com/pin/500744052301423641/
Source Yamachem
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Remixed from a design seen on Pixabay. The basic tile can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Honestly, who does not like a little pipe and mustache?
Source Luca Errico