Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A seamless background texture of old cardboard.
Source V. Hartikainen
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
These dots are already worn for you, so you don’t have to.
Source Matt McDaniel
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
A seamless background tile of aged paper with shabby look.
Source V. Hartikainen
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
This background image has seamless texture that resembles a surface of gray stone.
Source V. Hartikainen
I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin