Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
The image depicts a seamless pattern of pine tree leaves.
Source Yamachem
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
From a drawing of the coat of arms of the Ottoman Empire on Wikimedia.
Source Firkin
Zero CC tileable wood texture, made by me procedurally in Neo Texture Edit.
Source Sojan Janso
A seamless marble-like texture colored in light blue.
Source V. Hartikainen
There are many carbon patterns, but this one is tiny.
Source Designova
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'From Snowdon to the Sea. Striking stories of North and South Wales', Marie Trevelyan, 1895.
Source Firkin
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
The image depicts a seamless pattern made using a bird's face.
Source Yamachem
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A dark pattern made out of 3×3 circles and a 1px shadow. This works well as a carbon texture or background.
Source Atle Mo
Prismatic Abstract Geometric Background 2 No Black
Source GDJ
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso