From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Black And White Floral Pattern Background from PDP.
Source GDJ
A comeback for you: the popular Escheresque, now in black.
Source Patten
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
There are many carbon patterns, but this one is tiny.
Source Designova
Submitted by DomainsInfo – wtf, right? But hey, a free pattern.
Source DomainsInfo
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
Have you wondered about how it feels to be buried alive? Here is the pattern for it.
Source Hendrik Lammers
This is a seamless pattern which is derived from a flower petal image.
Source Yamachem
A frame using leaves from an image that was uploaded to Pixabay by mayapujiati
Source Firkin
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Prismatic Snowflakes Pattern No Background
Source GDJ
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Background Wall, Art Abstract, Watercolor Vintage style CC0 texture.
Source Ractapopulous
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
A seamless pattern made from the gold Penrose triangle by GDJ and the two remixes
Source Firkin
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo