Almost like little fish shells, or dragon skin.
Source Graphiste
Pattern #100! A black classic knit-looking pattern.
Source Factorio.us Collective
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
I guess this is inspired by the city of Ravenna in Italy and its stone walls.
Source Sentel
Here's a subtle marble-like background for use on websites.
Source V. Hartikainen
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Jardyne's Wife', Charles Wills, 1891.
Source Firkin
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i
Source Firkin
A light gray fabric pattern with faded vertical stripes.
Source V. Hartikainen
Zero CC tileable grass texture, photographed and made by me. CC0
Source Sojan Janso
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Black And White Floral Pattern Background Inverse
Source GDJ
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen
A seamless pattern of dark bricks. Maybe it's not very realistic, but it looks good in my opinion.
Source V. Hartikainen
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
This pack of filters can help you adding a blocky overlay to objects. May come handy at drawing blocks of stone.
Source Lazur URH
Number 3 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
More in the paper realm, this time with fibers.
Source Jorge Fuentes
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
An abstract texture of water. It's not perfect, but will do. You may download if you like it.
Source V. Hartikainen
Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran