Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
Sharp pixel pattern, just like the good old days.
Source Paridhi
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
A nice looking light gray background pattern with diagonal stripes.
Source V. Hartikainen
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Remixed from a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Prismatic Snowflakes Pattern No Background
Source GDJ
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
A simple bump filter made upon request at irc #inkscape at freenode. Made a screen capture of the making here: https://youtu.be/TGAWYKVLxQw
Source Lazur URH
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
A series of 5 patterns. That’s what the P stands for, if you didn’t guess it.
Source Dima Shiper