From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Design drawn in Paint.net, vectorised using Vector Magic and finished in Inkscape.
Source Firkin
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
Here's a new paper-like background for free use on personal and commercial projects (this applies to all background patterns here).
Source V. Hartikainen
Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A large (588x375px) sand-colored pattern for your ever-growing collection. Shrink at will.
Source Alex Tapein
Same classic 45-degree pattern, dark version.
Source Luke McDonald