Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
ZeroCC tileable stone texture, edited from pixabay, CC0
Source Sojan Janso
By popular request, an outline version of the pentagon pattern.
Source Atle Mo
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
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i
Source Firkin
Black paper texture, based on two different images.
Source Atle Mo
Based from Design Kindle
A pale olive green background with a seamless texture.
Source V. Hartikainen
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin