A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
It’s okay to be square! A nice light gray pattern with random squares.
Source Waseem Dahman
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
More in the paper realm, this time with fibers.
Source Jorge Fuentes
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
A large pattern with funky shapes and form. An original. Sort of origami-ish.
Source Luuk van Baars
This is a remix of "flower seamless pattern".I rotated the original image by 90 degrees.This is a seamless pattern of flowers.These horizontal wavy lines are one of Edo patterns which is called "tatewaku or tachiwaku or 立湧" that represents uprising steam or vapor.
Source Yamachem
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
This is a remix of "geometrical pattern 01".
Source Yamachem
Prismatic Abstract Geometric Background 5
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A seamless background texture of old cardboard.
Source V. Hartikainen
This is the remix of "Tileable Wave Pattern 2" uploaded by "Arvin61r58".Thanks.I added a wire-mesh fence seamless pattern as a lower layer.
Source Yamachem
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
Prismatic Geometric Pattern Background 2
Source GDJ