From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
This could be a hippy vintage wallpaper.
Source Tileable Patterns
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
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
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
This was formed by distorting an image of a background on Pixabay.
Source Firkin
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
A seamless pattern formed from background pattern 102
Source Firkin
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Might not be super subtle, but quite original in its form.
Source Alex Smith