I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Bumps, highlight and shadows – all good things.
Source Badhon Ebrahim
Prismatic Groovy Concentric Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A dark brown fabric-like background texture with seamless pattern of winding stripes.
Source V. Hartikainen
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Feel free to use this seamless background texture as a background on a web site. It's colored in a light pink color and is seamlessly tile-able.
Source V. Hartikainen
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
From drawing in 'Musings in Maoriland', Thomas Bracken, 1890.
Source Firkin
A set of paper filters. The base texture is generated the same way, only the compositing mode is varied.
Source Lazur URH
Heavily remixed from a drawing in 'Barbara Leybourne; a story of eighty years ago', Sarah Hamer, 1889.
Source Firkin
Remixed from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The image is the remix of "wire-mesh fence seamless pattern" .This is a more minute version of it.Sorry for the file size.Using path>difference in Inkscape, I will cut out any silhouette from this pattern and create a "meshed silhouette".
Source Yamachem
In the spirit of WWDC 2011, here is a dark iOS inspired linen pattern.
Source Atle Mo
A classic dark tile for a bit of vintage darkness.
Source Listvetra
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen