This one is something special. I’d call it a flat pattern, too. Very well done, sir!
Source GetDiscount
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Based on an image that was uploaded to Pixabay by devanath
Source Firkin
This is so subtle I hope you can see it! Tweak at will.
Source Alexandre Naud
Prismatic Abstract Geometric Background 5 No Black
Source GDJ
Everyone loves a diamond, right? Make your site sparkle.
Source AJ Troxell
A white version of the very popular linen pattern.
Source Ant Ekşiler
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
This one is amazing, truly original. Go use it!
Source Viahorizon
A seamless pattern formed from cross 4. To get the original tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Prismatic Groovy Concentric Background 4 No Black
Source GDJ
Background Wall, Art Abstract, Blue Well & CC0 texture.
Source Ractapopulous
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
Seamless Green Tile Background
Source V. Hartikainen
Simple combination of stripy squares with their negatively coloured counterparts
Source Firkin
A seamless pattern from a tile made from a jpg on Pixabay. To get the tile select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Background Wall, Art Abstract, Star Well & CC0 texture.
Source Ractapopulous
Mostly just mucked about with the colours and made one of the paths in the lead frame opaque. The glass remains transparent.
Source Firkin