A good starting point for a cardboard pattern. This would work well in a variety of colors.
Source Atle Mo
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Found on the ground in french cafe in kunming, Yunnan, china
Source Rejon
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Classic vertical lines, in all its subtlety.
Source Cody L
A seamless light gray paper texture with horizontal double lines.
Source V. Hartikainen
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
A new one called white wall, not by me this time.
Source Yuji Honzawa
A cute x, if you need that sort of thing.
Source Juan Scrocchi
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Might not be super subtle, but quite original in its form.
Source Alex Smith
He influenced us all. “Don’t be sad because it’s over. Smile because it happened.”
Source Atle Mo
Inspired by a pattern seen on a public domain image of a very old tile. To get the unit cell, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
I have no idea how to describe this one, but it’s light and delicate.
Source JBasoo
Remixed from a raster on Pixabay that was uploaded by ArtsyBee.
Source Firkin
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Same classic 45-degree pattern, dark version.
Source Luke McDonald
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
White handmade paper pattern with small bumps.
Source Marquis