There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
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
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I. Version with black background.
Source Firkin
The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
From a drawing in 'Less Black than we're painted', James Payn, 1884.
Source Firkin
A pattern formed from a photograph of a 16th century ceramic tile.
Source Firkin
It’s big, it’s gradient—and it’s square.
Source Brankic1979
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso