A seamless pattern formed from a sports car on clker.com. 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
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
From a drawing in 'An Old Maid's Love. A Dutch tale told in English', Maarten Maartens, 1891.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Sounds like something from World of Warcraft. Has to be good.
Source Tony Kinard
This could be a hippy vintage wallpaper.
Source Tileable Patterns
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Green Web Background, Seamless tile.
Source V. Hartikainen
Prismatic Abstract Geometric Background 4
Source GDJ
Zero CC tileable pine bark texture, photographed and made by me. CC0
Source Sojan Janso