A comeback for you: the popular Escheresque, now in black.
Source Patten
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
Remixed from a JPG that was uploaded to Pixabay by susanlu4esm
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
From a drawing in 'Artists and Arabs', Henry Blackburn, 1868
Source Firkin
You may use it as is, or modify it as you like.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
As simple and subtle as it gets. But sometimes that’s just what you want.
Source Designova
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
A seamless pattern created from a square tile. To get the tile, select the pattern in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Might not be super subtle, but quite original in its form.
Source Alex Smith
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Zero CC tileable bark texture, photographed and made by me. CC0
Source Sojan Janso