Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
From a drawing in 'La Principauté de Liège et les Pays-Bas au XVIe siècle', Société des Bibliophiles Liégeois ,1887.
Source Firkin
A seamless texture of a rough concrete surface.
Source V. Hartikainen
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Dark pattern with some nice diagonal stitched lines crossing over.
Source Ashton
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
No idea what Nistri means, but it’s a crisp little pattern nonetheless.
Source Markus Reiter
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
You know I’m a sucker for these. Well-crafted paper pattern.
Source Mihaela Hinayon
Embossed lines and squares with subtle highlights.
Source Alex Parker
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Element of beach pattern with background.
Source Rones
A large (588x375px) sand-colored pattern for your ever-growing collection. Shrink at will.
Source Alex Tapein
More leather, and this time it’s bigger! You know, in case you need that.
Source Elemis
A comeback for you: the popular Escheresque, now in black.
Source Patten
Dark blue concrete wall with some small dust spots.
Source Atle Mo
Small dots with minor circles spread across to form a nice mosaic.
Source John Burks
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen