Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
An alternative colour scheme to the original seamless pattern.
Source Firkin
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
Prismatic Basic Pattern 2 No Background
Source GDJ
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
Black brick wall pattern. Brick your site up!
Source Alex Parker
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Beautiful dark noise pattern with some dust and grunge.
Source Vincent Klaiber
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight