Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Colour version of the original pattern inspired by the front cover of 'Old and New Paris', Henry Edwards, 1894.
Source Firkin
A seamless background pattern with impressed gray dots.
Source V. Hartikainen
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
This is so subtle: We’re talking 1% opacity. Get your squint on!
Source Atle Mo
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Prismatic Hexagonalist Pattern No Background
Source GDJ
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Prismatic 3D Isometric Tessellation Pattern 6
Source GDJ
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous