I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
A chequerboard pattern with a fruit theme. The fruits are from a posting by inkscapeforum.it.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
A version without colours blended together to give a different look.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
As far as fabric patterns goes, this is quite crisp.
Source Heliodor Jalba
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
Prismatic Chevrons Pattern 5 With Background
Source GDJ
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
This is indeed a bit strange, but here’s to the crazy ones!
Source Christopher Buecheler
Zero CC tileable hard cover red book, scanned and made by me. CC0
Source Sojan Janso
A new one called white wall, not by me this time.
Source Yuji Honzawa
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Abstract Geometric Background 2 No Black
Source GDJ