Might not be super subtle, but quite original in its form.
Source Alex Smith
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Looks like an old rug or a computer chip.
Source Patutin Sergey
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Prismatic Abstract Geometric Background 5
Source GDJ
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
A seamless pattern created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Gold Triangular Seamless Pattern No Background
Source GDJ
Farmer could be some sort of fabric pattern, with a hint of green.
Source Fabian Schultz
Abstract Tiled Background Extended 6
Source GDJ
A pale yellow background pattern with vertical stripes. The stripes are partially faded. I think this background image turned out pretty well, especially those faded stripes.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
Looks a bit like concrete with subtle specks spread around the pattern.
Source Mladjan Antic
Otis Ray Redding was an American soul singer-songwriter, record producer, arranger, and talent scout. So you know.
Source Thomas Myrman
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
A seamless pattern with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen