A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Prismatic Chevrons Pattern 5 With Background
Source GDJ
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
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
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
An abstract Background pattern of purple twisty patterns.
Source TikiGiki
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Formed from decorative divider 184 in paint.net. Vectorised with Vector Magic.
Source Firkin
A seamless canvas texture for using as background on websites. Colored in pale tones of brown.
Source V. Hartikainen
The rectangular tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin