Tessellation 16 (colour 6) #2210
 Colorful  CC 0

The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i

Source Firkin

 More Textures
Background pattern 308 (colour 2) #1871
 Green  CC 0

Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.

Source Firkin

Background pattern 266 #2068
 Dark  CC 0

Remixed from a drawing in 'Some account of the Worshipful Company of Ironmongers', John Nicholl, 1866.

Source Firkin

Broken Noise@2X #365
 Dark  CC BY-SA 3.0

Beautiful dark noise pattern with some dust and grunge.

Source Vincent Klaiber

Prismatic Abstract Geometric Background 4 No Black #441
 Dark  CC 0

Prismatic Abstract Geometric Background 4 No Black

Source GDJ