People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Alternative colour scheme for the original floral pattern.
Source Firkin
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin
Inspired by a drawing in 'Kulturgeschichte', Freidrich Hellwald, 1896.
Source Firkin
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A simple circle. That’s all it takes. This one is even transparent, for those who like that.
Source Saqib
Fix side and a seamless pattern formed from circles.
Source SliverKnight
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso
Wild Oliva or Oliva Wilde? Darker than the others, sort of a medium dark pattern.
Source Badhon Ebrahim
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic 3D Isometric Tessellation Pattern 6
Source GDJ
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
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
Abstract Tiled Background Extended 11
Source GDJ
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
Prismatic Chevrons Pattern 5 With Background
Source GDJ
Derived from a drawing in 'Elfrica. An historical romance of the twelfth century', Charlotte Boger, 1885
Source Firkin
It’s a hole, in a pattern. On your website. Dig it!
Source Josh Green