Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Light square grid pattern, great for a “DIY projects” sort of website, maybe?
Source Rafael Almeida
Remixed from an image that was uploaded to Pixabay by CatherineClennan
Source Firkin
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
Mostly just mucked about with the colours and made one of the paths in the lead frame opaque. The glass remains transparent.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
A seamless pattern recreated from an image on Pixabay. It is reminiscent of parquet flooring and is formed from a square tile, which can be recovered in Inkscape by selecting the ungrouped rectangle and using shift-alt-I together.
Source Firkin
Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
A seamless paper background colored in pale yellow.
Source V. Hartikainen
Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
A seamlessly tileable pink background texture.
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Geometric lines are always hot, and this pattern is no exception.
Source Listvetra
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin