Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
Green Web Background, Seamless tile.
Source V. Hartikainen
To celebrate the new feature, we need some sparkling diamonds.
Source Atle Mo
White little knobs, coming in at 10x10px. Sweet!
Source Amos
Use shift+alt+i on the selected rectangle in Inkscape to get the tile this is based on
Source Firkin
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
A repeating background of beige (or is it more vanilla yellow) textured stripes. One more background with stripes.
Source V. Hartikainen
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
The starting point for this was drawn on the web site steamcoded.org/PolyskelionMaker.svg
Source Firkin
Classic 45-degree pattern, light version.
Source Luke McDonald
Here's a new background image for websites with a seamless pink texture. It should look beautiful with website themes where light pink background is needed. The background is seamless, therefore it should be used as a tiled background.
Source V. Hartikainen
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
From a drawing in 'Handbook of the excursions proposed to be made by the Lincoln Diocesan Architectural Society, on the 27th and 28th of May, 1857', Edward Trollope, 1857.
Source Firkin
It’s an egg, in the form of a pattern. This really is 2012.
Source Paul Phönixweiß
A rusty grunge background for websites. Feel free to use it in your site's theme.
Source V. Hartikainen
Prismatic Abstract Background Design
Source GDJ
This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen
Colourful background achieved with gradient fills.
Source Firkin
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
White circles connecting on a light gray background.
Source Mark Collins
Colour version that is close to the original drawing uploaded to Pixabay by pencilparker.
Source Firkin
A free seamless background image with a texture of dark red "canvas". It should look very nice on web sites.
Source V. Hartikainen