From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
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
Prismatic Curved Diamond Pattern No Background
Source GDJ
A seamless web texture of "green stone".
Source V. Hartikainen
A free tileable background colored in off-white (antique white) color.
Source V. Hartikainen
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
A pattern formed from a photograph of a 16th century ceramic tile.
Source Firkin
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen
A seamless design of flowers remixed from a jpg on Pixabay by Prawny.
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
Prismatic Hypnotic Pattern No Background
Source GDJ
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso
Colour version of a pattern that came out of playing with the 'light rays' plug-in for Paint.net
Source Firkin
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
You know, tiny and sharp. I’m sure you’ll find a use for it.
Source Atle Mo
Retro Circles Background 5 No Black
Source GDJ
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
A version without colours blended together to give a different look.
Source Firkin