This is so subtle you need to bring your magnifier!
Source Carlos Valdez
Super subtle indeed, a medium gray pattern with tiny dots in a grid.
Source Designova
ZeroCC tileabel stone granite texture, edited from pixabay. CC0
Source Sojan Janso
Basket Fibers, Basket Texture, Braid Background style CC0 texture.
Source 1A-Photoshop
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
Formed by heavily distorting part of a an image of a fish uploaded to Pixabay by GLady
Source Firkin
A grid of squares with green colours. Since the colours are randomly distributed it is automatically seamless.
Source Firkin
Pass parameters to the URL or edit the source code variables to configure the graph paper for the division desired.
Source JayNick
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A lovely light gray pattern with stripes and a dash of noise.
Source V. Hartikainen
This beige background pattern resembles a concrete wall with engravings or something similar to it.
Source V. Hartikainen
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Light and tiny, just the way you like it.
Source Rohit Arun Rao
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin