Real snow that tiles, not easy. This is not perfect, but an attempt.
Source Atle Mo
The base gradient edited so now more details are rendered.
Source Lazur URH
A beautiful dark wood pattern, superbly tiled.
Source Omar Alvarado
Here's a bluish gray striped background pattern for use on web sites.
Source V. Hartikainen
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Prismatic Geometric Pattern Background 2
Source GDJ
Inspired by a drawing seen in 'City of Liverpool', James Picton, 1883.
Source Firkin
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
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 traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Basic Pattern 2 No Background
Source GDJ
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A dark metallic background with a pattern of stamped dots. Here's a dark "metallic" background pattern for you.
Source V. Hartikainen
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
Here's a new gray "fabric" pattern. Use it as backgrounds for websites or for other purposes.
Source V. Hartikainen
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin