The tile this fill pattern is based on can be had by using shift+alt+i on the rectangle.
Source Firkin
Abstract Ellipses Background Grayscale
Source GDJ
Remixed from a drawing in 'Some account of the Worshipful Company of Ironmongers', John Nicholl, 1866.
Source Firkin
Zero CC tileable moss or lichen covered stone texture, edited from pixabay. CC0
Source Sojan Janso
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
Background pattern originally a PNG drawn in Paint.net
Source Firkin
Zero CC tileable hard cover cells, skin like, book texture. 4K, Scanned and made by me CC0
Source Sojan Janso
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Don’t look at this one too long if you’re high on something.
Source Luuk van Baars
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Seamless Green Tile Background
Source V. Hartikainen
The tile can be had by using shift+alt+i on the selected rectangle in Inkscape
Source Firkin
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
A seamless pattern of leopard skin. It should look nice as a background element on web pages.
Source V. Hartikainen
Embossed lines and squares with subtle highlights.
Source Alex Parker
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
The starting point for this was drawn on the web site steamcoded.org/PolyskelionMaker.svg
Source Firkin
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
A beautiful dark padded pattern, like an old classic sofa.
Source Chris Baldie