A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
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
A repeating gloomy background image. This one consists of a pattern of black chains layered on top of a dark textured background.
Source V. Hartikainen
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
You just can’t get enough of the fabric patterns, so here is one more for your collection.
Source Krisp Designs
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A seamlessly tileable pink background texture.
Source V. Hartikainen
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
Remixed from a drawing in 'Prehistoric Man: researches into the origin of civilisation in the old and the new world', Daniel Wilson, 1876.
Source Firkin
Colored maple leaves scattered on a surface. This is tileable, so it can be used as a background or wallpaper.
Source Eady
From a drawing in 'Uit de geschiedenis der Heilige Stede te Amsterdam', Yohannes Sterck, 1898.
Source Firkin
Prismatic Floral Background No Black
Source GDJ
A seamless pattern from a tile drawn in Paint.net and vectorised in Vector Magic
Source Firkin
I asked Gjermund if he could make a pattern for us – result!
Source Gjermund Gustavsen