Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
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
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
A bit like some carbon, or knitted netting if you will.
Source Anna Litvinuk
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Nicely crafted paper pattern, although a bit on the large side (500x593px).
Source Blaq Annabiosis
A version without colours blended together to give a different look.
Source Firkin
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
I love cream! 50x50px and lovely in all the good ways.
Source Thomas Myrman
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
A seamlessly tile-able grunge background image.
Source V. Hartikainen
From a drawing in 'Royal Ramsgate', James Simson, 1897.
Source Firkin
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
I’m not going to lie – if you submit something with the words Norwegian and Rose in it, it’s likely I’ll publish it.
Source Fredrik Scheide
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
Zero CC tileable hard cover red book, scanned and made by me. CC0
Source Sojan Janso
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin