Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Prismatic Chevrons Pattern 5 With Background
Source GDJ
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac
A pale orange background pattern with glossy groove stripes.
Source V. Hartikainen
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
This seamless light brown background texture resembles a wallpaper with vertical stripes. One way to use it is as a tiled background on web sites.
Source V. Hartikainen
Zero CC tileable ground cracked, crackled, texture, made by me.
Source Sojan Janso
The classic 45-degree diagonal line pattern, done right.
Source Jorick van Hees
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
Alternative colour scheme for the original floral pattern.
Source Firkin
A slightly more textured pattern, medium gray. A bit like a potato sack?
Source Bilal Ketab
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
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
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Abstract Tiled Background Extended 8
Source GDJ