Not so subtle. These tileable wood patterns are very useful.
Source Elemis
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Same as gray sand but lighter. A sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
White circles connecting on a light gray background.
Source Mark Collins
Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
The image is a remix of "edo pattern-samekomon".I changed the color of dots from black to white and added BG in light-brown.
Source Yamachem
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A seamlessly repeating background pattern of wood. The image is procedurally generated, and, I think, it's turned out quite well.
Source V. Hartikainen