Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Seamless SVG vector and JPG backgrounds with faded diagonal stripes. The colors are editable.
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Tiny circle waves, almost like the ocean.
Source Sagive
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
Retro Circles Background 5 No Black
Source GDJ
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
A nice and simple white rotated tile pattern.
Source Another One
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
This one has rusty dark brown texture.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from a drawing in 'Jezebel's Daughter', Wilkie Collins 1880
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
This one is quite simple in design, it consists of vertical stripes layered on top of a seamless texture.
Source V. Hartikainen
This is a grid, only it’s noisy. You know. Reminds you of those printed grids you draw on.
Source Vectorpile
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
Used in small doses, this could be a nice subtle pattern. Used on a large surface, it’s dirty!
Source Paul Reulat
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Prismatic Geometric Tessellation Pattern 3 No Background
Source GDJ
This background pattern contains a seamless texture of bark. It's not very realistic, but I think it looks quite nice.
Source V. Hartikainen