Dare I call this a «flat pattern»? Probably not.
Source Dax Kieran
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
This background pattern has futuristic look. So, maybe it could be used on websites or blogs dedicated to video games?!
Source V. Hartikainen
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
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
Prismatic Geometric Tessellation Pattern No Background
Source GDJ
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
Adapted from a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Just what the name says, paper fibers. Always good to have.
Source Heliodor jalba
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
A free light orange brown wallpaper with vertical stripes designed for use as a tiled background on websites. An yet another background pattern with vertical stripes.
Source V. Hartikainen
Black brick wall pattern. Brick your site up!
Source Alex Parker
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward
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
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
A heavy dark gray base, some subtle noise and a 45-degree grid makes this look like a pattern with a tactile feel to it.
Source Atle Mo
Colorful Floral Background 3 No Black
Source GDJ
A seamless web background with texture of aged grid paper.
Source V. Hartikainen
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ