CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
From an image on opengameart.org shared by rubberduck.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A dark metallic background with a pattern of stamped dots. Here's a dark "metallic" background pattern for you.
Source V. Hartikainen
Fabric-ish patterns are close to my heart. French Stucco to the rescue.
Source Christopher Buecheler
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Derived from elements found in a floral ornament drawing on Pixabay.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
One more in the line of patterns inspired by Japanese/Asian styles. Smooth.
Source Kim Ruddock
A gray background pattern with a texture of textile. Suits perfectly for web design.
Source V. Hartikainen
A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
The tile can be had by using shift+alt+i on the selected rectangle in Inkscape
Source Firkin
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Kaleidoscope Prismatic Abstract No Background
Source GDJ
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
I love cream! 50x50px and lovely in all the good ways.
Source Thomas Myrman
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
White fabric looking texture with some nice random wave features.
Source Hendrik Lammers
From a drawing in 'Royal Ramsgate', James Simson, 1897.
Source Firkin
The tile for this is based on a repeating unit close to a design on Pixabay. It can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin