ZeroCC tileable stone texture, edited from pixabay, CC0
Source Sojan Janso
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Actually remixed from a pattern on Pixabay. But then noticed a very similar one on Openclipart.org uploaded by btj51q2.
Source Firkin
A seamless pattern formed from a square tile based on a jpg on Pixabay. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
A seamless background of warped stripes on paper.
Source V. Hartikainen
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
The classic notebook paper with horizontal stripes.
Source Are Sundnes
This background pattern looks like bamboo to me. Feel free to download it for your website (for your blog perhaps?).
Source V. Hartikainen
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
More carbon fiber for your collections. This time in white or semi-dark gray.
Source Badhon Ebrahim
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
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
Pattern Background, Texture, Photoshop Structure style CC0 texture.
Source Darkmoon1968
A textured orange background pattern with vertical stripes.
Source V. Hartikainen
Geometric triangles seem to be quite hot these days.
Source Pixeden
White circles connecting on a light gray background.
Source Mark Collins
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin