An emulated “transparent” background pattern, like that of all kinds of computer graphics software.
Source AdamStanislav
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Prismatic Groovy Concentric Background 2
Source GDJ
Remixed from a JPG that was uploaded to Pixabay by Osckar
Source Firkin
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall