Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Fix side and a seamless pattern formed from circles.
Source SliverKnight
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
Honestly, who does not like a little pipe and mustache?
Source Luca Errico
Prismatic Geometric Pattern Background 2
Source GDJ
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
The Grid. A digital frontier. I tried to picture clusters of information as they traveled through the computer.
Source Haris Šumić
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin