Might not be super subtle, but quite original in its form.
Source Alex Smith
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
This background texture resembles stone. It may be used as a background on web pages or on some of their html elements (header, borders, menu bar, etc.). Just modify it for your needs.
Source V. Hartikainen
A version without colours blended together to give a different look.
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by DavidZydd
Source Firkin
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
Classic vertical lines, in all its subtlety.
Source Cody L
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
A yellow tiled background... Blurriness, bokeh effect and rectangles pattern in one mix.
Source V. Hartikainen
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Almost like little fish shells, or dragon skin.
Source Graphiste
A seamless green background texture. The image is distributed under a Creative Commons License (like all of the images here).
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin