A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Prismatic Abstract Line Art Pattern Background
Source GDJ
It has waves, so make sure you don’t get sea sickness.
Source CoolPatterns
A white version of the very popular linen pattern.
Source Ant Ekşiler
Sometimes you just need the simplest thing.
Source Fabricio
Prismatic Geometric Pattern Background 2
Source GDJ
Derived from a drawing in 'Elfrica. An historical romance of the twelfth century', Charlotte Boger, 1885
Source Firkin
A bit of scratched up grayness. Always good.
Source Dmitry
Number 2 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
A seamless pattern formed from a tile made from page ornament 22. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Abstract Background Design
Source GDJ
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
Derived from an image that was uploaded to Pixabay by pugmom40
Source Firkin