From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The name alone is awesome, but so is this sweet dark pattern.
Source Federica Pelzel
Black And White Floral Pattern Background from PDP.
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Geometric triangles seem to be quite hot these days.
Source Pixeden
Prismatic Hypnotic Pattern No Background
Source GDJ
A dark background pattern/texture of a dimpled metal plate.
Source V. Hartikainen
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
A background tile of dark textile. Made this a long time ago and just now decided to publish it.
Source V. Hartikainen
Everyone needs some stardust. Sprinkle it on your next project.
Source Atle Mo
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
This is the remix of an Openclipart clipart called "Maze" uploaded by "any_ono_mous".Thanks.This is a seamless pattern of a maze.
Source Yamachem
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Retro Circles Background 7 No Black
Source GDJ
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Remixed from a drawing in 'Line and form", Walter Crane, 1914.
Source Firkin