A heavy hitter at 400x400px, but lovely still.
Source Breezi
Derived from an image that was uploaded to Pixabay by TheDigitalArtist
Source Firkin
Prismatic Floral Background No Black
Source GDJ
Seamless pattern formed from a tile that can be had by selecting the rectangle in Inkscape and using 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
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
This one has rusty dark brown texture.
Source V. Hartikainen
Tiny little fibers making a soft and sweet look.
Source Badhon Ebrahim
I took the liberty of using Dmitry’s pattern and made a version without perforation.
Source Atle Mo
Drawn in Paint.net using the kaleidoscope plug-in and vectorised.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
A light gray wall or floor (you decide) of concrete.
Source Atle Mo