In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
More Japanese-inspired patterns, Gold Scales this time.
Source Josh Green
Prismatic Chevrons Pattern 5 With Background
Source GDJ
Smooth Polaroid pattern with a light blue tint.
Source Daniel Beaton
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A cute x, if you need that sort of thing.
Source Juan Scrocchi
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
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin