Not so subtle. These tileable wood patterns are very useful.
Source Elemis
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A black tile-able background with paper-like texture.
Source V. Hartikainen
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a drawing in 'Incidents on a Journey through Nubia to Darfoor', F. Ensor, 1891.
Source Firkin
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
Fake or not, it’s quite luxurious.
Source Factorio.us Collective
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Subtle scratches on a light gray background.
Source Andrey Ovcharov
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Farmer could be some sort of fabric pattern, with a hint of green.
Source Fabian Schultz
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
A seamless web texture of "green stone".
Source V. Hartikainen
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
Zero CC tileable Laminate wood texture, photographed and made by me. CC0
Source Sojan Janso