Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
Sort of like the back of a wooden board. Light, subtle, and stylish, just the way we like it!
Source Nikolalek
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
This seamless pattern consists of a blue grid on a yellow background.
Source V. Hartikainen
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
Might not be super subtle, but quite original in its form.
Source Alex Smith
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Very dark pattern with some noise and 45-degree lines.
Source Stefan Aleksić
Here's a tile-able wood background image for use in web design.
Source V. Hartikainen
A repeating background for websites with a texture of black groove stripes.
Source V. Hartikainen
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
Classic vertical lines, in all its subtlety.
Source Cody L
Pass parameters to the URL or edit the source code variables to configure the graph paper for the division desired.
Source JayNick
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
As the original image 's page size is too large for its image size, I remixed it.
Source Yamachem