A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Derived from an image that was uploaded to Pixabay by Kaz
Source Firkin
Abstract Tiled Background Extended 12
Source GDJ
CC0 remixed from a drawing. Walter Crane, 1914, Firkin.
Source SliverKnight
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Small gradient crosses inside 45-degree boxes, or bigger crosses if you will.
Source Wassim
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
One more brick pattern. A bit more depth to this one.
Source Benjamin Ward