From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Prismatic Groovy Concentric Background 5
Source GDJ
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
Awesome name, great pattern. Who does not love space?
Source Nick Batchelor
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Sharp pixel pattern, just like the good old days.
Source Paridhi
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
The image depicts a seamless pattern of a snow crystal.I referred to a book called ”sekka-zusetsu” or "雪華図説" which means an illustrated explanation about snow crystals.This book was published in 1832 (天保3年) or Edo period.For more about "雪華図説",see here:dl.ndl.go.jp/info:ndljp/pid/2536975
Source Yamachem
Neat little photography icon pattern.
Source Hossam Elbialy