This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
From an image on opengameart.org shared by rubberduck.
Source Firkin
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A dark striped seamless pattern suitable for use as a background on websites.
Source V. Hartikainen
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Submitted as a black pattern, I made it light and a few steps more subtle.
Source Andy
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
Lovely pattern with some good-looking non-random noise lines.
Source Zucx
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
Psychedelic Geometric Background No Black
Source GDJ
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
"Beige Stone", Tileable Texture.
Source V. Hartikainen
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Inspired by a pattern found in 'A General History of Hampshire, or the County of Southampton, including the Isle of Wight', Bernard Woodwood, 1861
Source Firkin
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Used the 6th circle pattern designed by Viscious-Speed to create a print that can be used for card making or scrapbooking. Save as a PDF file for the best printing option.
Source Lovinglf
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin