Geometric triangles seem to be quite hot these days.
Source Pixeden
Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
Love me some light mesh on a Monday. Sharp.
Source Wilmotte Bastien
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
It looks like a polished stone surface to me. Download it for free, as always.
Source V. Hartikainen
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
A beautiful dark padded pattern, like an old classic sofa.
Source Chris Baldie
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
A comeback for you: the popular Escheresque, now in black.
Source Patten
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
The image depicts polka dot seamless pattern.
Source Yamachem
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
A seamless background of warped stripes on paper.
Source V. Hartikainen
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen