A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
Remixed from a PNG that was uploaded to Pixabay by k_jprather
Source Firkin
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
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
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
This ladies and gentlemen, is texturetastic! Love it.
Source Adam Pickering
Seamless pattern inspired by a drawing on Pixabay. To get the tile this is formed from, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A grayscale fabric pattern with vertical lines of stitch holes.
Source V. Hartikainen
A very dark asfalt pattern based off of a photo taken with my iPhone.
Source Atle Mo
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Dark, lines, noise, tactile. You get the drift.
Source Anatoli Nicolae
Adapted from an image that was uploaded to Pixabay by Anerma.
Source Firkin
Derived from a corner decoration itself found as a jpg on Pixabay.
Source Firkin
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
A seamless background pattern with a texture of wood planks. This wood background pattern has vertically arranged planks. You may try to rotate it 90°, to see how it will look like when the wood planks are arranged horizontally.
Source V. Hartikainen
U.S.-based National Fire Protection Association standard fire diamond for flagging risks posed by hazardous materials. The red diamond has a number 0-4 depending on flammability. The blue diamond has a number 0-4 depending on health hazard. The yellow has a number 0-4 depending on reactivity. the white square has a special notice, e.g OX for oxidizer.
Source Firkin
A classic dark tile for a bit of vintage darkness.
Source Listvetra