The image depicts a seamless pattern of a snow crystal.I referred to a book called ”sekka-zusetsu” or "雪華図説" which means an illustrated explanation about snow crystals.This book was published in 1832 (天保3年) or Edo period.For more about "雪華図説",see here:dl.ndl.go.jp/info:ndljp/pid/2536975
Source Yamachem
Looks like an old rug or a computer chip.
Source Patutin Sergey
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
From an image on opengameart.org shared by rubberduck.
Source Firkin
Pattern that came out of playing with the 'slinky' plug-in for Paint.net
Source Firkin
A repeating background of beige paper with vintage look. Repeats to infinity, as usual.
Source V. Hartikainen
Greyscale version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
A large (588x375px) sand-colored pattern for your ever-growing collection. Shrink at will.
Source Alex Tapein
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
Prismatic Abstract Geometric Background 2
Source GDJ
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
Kaleidoscope Prismatic Abstract No Background
Source GDJ
A seamless texture of worn out "cardboard".
Source V. Hartikainen
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin