Same classic 45-degree pattern, dark version.
Source Luke McDonald
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo
Nasty or not, it’s a nice pattern that tiles. Like they all do.
Source Badhon Ebrahim
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
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
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Tile available in Inkscape using shift-alt-i on the selected rectangle
Source Firkin
It’s an egg, in the form of a pattern. This really is 2012.
Source Paul Phönixweiß
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
I skipped number 3, because it wasn’t all that great. Sorry.
Source Dima Shiper
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen