The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i
Source Firkin
Inspired by this, I came up with this pattern. Madness!
Source Atle Mo
Three shades of gray makes this pattern look like a small carbon fiber surface. Great readability even for small fonts.
Source Atle Mo
ZeroCC tileable stone texture, edited from pixabay, CC0
Source Sojan Janso
Can never have too many knitting patterns, especially as nice as this.
Source Victoria Spahn
Recreated from a pattern found in 'Az Osztrák-Magyar Monarchia irásban és képben', 1882. To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
Colorful Floral Background 3 No Black
Source GDJ
A seamless pattern the starting point for which was a 'colour modulo' texture in Paint.net.
Source Firkin
Prismatic Groovy Concentric Background
Source GDJ
This is sort of fresh, but still feels a bit old school.
Source Martuchox
From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i
Source Firkin
This one is amazing, truly original. Go use it!
Source Viahorizon
Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
Different from the original in being a simple tile stored as a pattern definition, rather than numerous repeated objects. Hence easy and quick to give this pattern to objects of different shapes. To get the tile in Inkscape, select the rectangle and use shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin