Not so subtle. These tileable wood patterns are very useful.
Source Elemis
This tiled background comes in red and consists of tiles that look like gemstones. It is more for blogs or social profiles, I think.
Source V. Hartikainen
Seamless pattern made from a tile that can be obtained in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Abstract Tiled Background Extended 8
Source GDJ
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
Abstract Tiled Background Extended 12
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
This is the remix of an OCAL clipart called "Art Nouveau ornament" uploaded by "microcosme".Thanks.This is a seamless pattern of an Art Nouveau ornament.
Source Yamachem
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
There are many carbon patterns, but this one is tiny.
Source Designova
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
"Beige Stone", Tileable Texture.
Source V. Hartikainen
Sort of reminds me of those old house wallpapers.
Source Tish
Remixed from a drawing in 'Очерки Русской Исторіи въ памятникахъ быта', Petr Polevoi, 1879.
Source Firkin
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin