The act or state of corrugating or of being corrugated, a wrinkle; fold; furrow; ridge.
Source Anna Litvinuk
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Black And White Floral Pattern Background from PDP.
Source GDJ
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
Just like the black maze, only in light gray. Duh.
Source Peax
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Tiny circle waves, almost like the ocean.
Source Sagive
Background Wall, Art Abstract, white Well & CC0 texture.
Source Ractapopulous
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
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
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
ZeroCC tileable mossy (lichen) stone texture, edited from pixabay. CC0
Source Sojan Janso
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A repeatable image with dark background and metal grid pattern.
Source V. Hartikainen