In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
Prismatic Hypnotic Pattern No Background
Source GDJ
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
No relation to the band, but damn it’s subtle!
Source Thomas Myrman
This one is amazing, truly original. Go use it!
Source Viahorizon
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A gray background pattern with a texture of textile. Suits perfectly for web design.
Source V. Hartikainen
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
The image depicts a Japanese Edo pattern called "kanoko or 鹿の子" meaning "fawn" which has a fur with small white spots.
Source Yamachem
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
A dark background pattern/texture of a dimpled metal plate.
Source V. Hartikainen
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Background formed from the original with an emboss effect.
Source Firkin
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
Luxury pattern, looking like it came right out of Paris.
Source Daniel Beaton
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
Super dark, crisp and detailed. And a Kill Bill reference.
Source Badhon Ebrahim
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Prismatic Hypnotic Pattern 2 No Background
Source GDJ