The image depicts an edo-era pattern called "same-komon" or "鮫小紋"which looks like a shark skin.The "same" in Japanese means shark in English.
Source Yamachem
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Psychedelic Geometric Background No Black
Source GDJ
Used a cherry by doctormo to make this seamless pattern
Source Firkin
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
One more sharp little tile for you. Subtle circles this time.
Source Blunia
Alternative colour scheme. 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
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
The image depicts meshed silhouettes of various things.The original image is an OCAL clipart called "Enter FOSSASIA 2016 #IoT T-shirt Design Contest" uploaded by "openclipart".Thanks.
Source Yamachem
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
A cute x, if you need that sort of thing.
Source Juan Scrocchi
Prismatic Groovy Concentric Background 4
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
An attempt for cleaning up the original image in a few steps.
Source Lazur URH