A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper
Prismatic Triangular Background Design Mark II 5
Source GDJ
This one needs to be used in small areas; you can see it repeat.
Source Luca
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
U.S.-based National Fire Protection Association standard fire diamond for flagging risks posed by hazardous materials. The red diamond has a number 0-4 depending on flammability. The blue diamond has a number 0-4 depending on health hazard. The yellow has a number 0-4 depending on reactivity. the white square has a special notice, e.g OX for oxidizer.
Source Firkin
Remixed from a drawing in 'Paul's Sister', Frances Peard, 1889.
Source Firkin
Fix and cc0 to get the tile this is based on.
Source SliverKnight
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Formed by distorting an image on Pixabay that was uploaded by gustavorezende. To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
A seamless background of warped stripes on paper.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
This is so subtle you need to bring your magnifier!
Source Carlos Valdez
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
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
From a drawing in 'Two Women in the Klondike', Mary Hitchcock, 1899.
Source Firkin
Remixed from a PNG that was uploaded to Pixabay by k_jprather
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen