A seamless pattern with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers
Sharp pixel pattern, just like the good old days.
Source Paridhi
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
A pattern derived from repeating unit cells each derived from part of a mosaic in paint.net. The starting point for the mosaic was a picture of some prawns!
Source Firkin
Prismatic Polyskelion Pattern No Background
Source GDJ
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Abstract Geometric Monochrome Pattern Prismatic No Background
Source GDJ
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
The original enhanced with some gradients.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
You know you can’t get enough of these linen-fabric-y patterns.
Source James Basoo
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Prismatic Abstract Geometric Background 4 No Black
Source GDJ
Remixed from a drawing that was uploaded to Pixabay by captenpub.
Source Firkin
Has nothing to do with toast, but it’s nice and subtle.
Source Pippin Lee
Pattern produced in Paint.net using the Vibrato plug-in.
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