This reminds me of Game Cube. A nice light 3D cube pattern.
Source Sander Ottens
Psychedelic Geometric Background No Black
Source GDJ
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
It’s an egg, in the form of a pattern. This really is 2012.
Source Paul Phönixweiß
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
The tile this is formed from can be retrieved in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
A seamless pattern made from the gold Penrose triangle by GDJ and the two remixes
Source Firkin
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Prismatic Abstract Geometric Background 4
Source GDJ