Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Zero CC tileable ground cracked, crackled, texture, made by me.
Source Sojan Janso
This light blue background pattern is quite pleasing to the eye, it consists of a tiny rough grid pattern, which is seamless by design. That's it, if you like the color, you can use this seamless pattern in a web design without making any further modifications to it.
Source V. Hartikainen
This one is amazing, truly original. Go use it!
Source Viahorizon
Derived from a drawing in 'Historiske Afhandlinger', Adolf Jorgensen, 1898.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Utilising a bird from s-light and some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
A comeback for you: the popular Escheresque, now in black.
Source Patten
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Little x’es, noise and all the stuff you like. Dark like a Monday, with a hint of blue.
Source Tom McArdle
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
A seamless textured paper for backgrounds. Colored in pale orange hues.
Source V. Hartikainen
Sounds French. Some 3D square diagonals, that’s all you need to know.
Source Graphiste
Remixed from a PNG that was uploaded to Pixabay by gingertea
Source Firkin
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
I’m not going to use the word Retina for all the new patterns, but it just felt right for this one. Huge wood pattern for ya’ll.
Source Atle Mo
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin