Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
It’s big, it’s gradient—and it’s square.
Source Brankic1979
The classic subtle pattern. Sort of wall/brick looking. Or moon-looking?
Source Joel Klein
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A new take on the black linen pattern. Softer this time.
Source Atle Mo
Light gray paper pattern with small traces of fiber and some dust.
Source Atle Mo
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
A seamless pattern formed from miutopia mug remixes on a tablecloth.
Source Firkin
Prismatic Groovy Concentric Background 4
Source GDJ