The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The image is a design of blue glass.How about using it as background image?
Source Yamachem
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
This tiled background comes in red and consists of tiles that look like gemstones. It is more for blogs or social profiles, I think.
Source V. Hartikainen
Never out of fashion and so much hotter than the 45º everyone knows, here is a sweet 60º line pattern.
Source Atle Mo
A background pattern with blue on white vertical stripes.
Source V. Hartikainen
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
Prismatic Triangular Background Design Mark II 5
Source GDJ
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
A pattern formed from a photograph of a 16th century ceramic tile.
Source Firkin
A background tile for web with abstract repeating texture of dark "stone wall".
Source V. Hartikainen
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
Your eyes can trip a bit from looking at this – use it wisely.
Source Michal Chovanec
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning