Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
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
A simple but elegant classic. Every collection needs one of these.
Source Christopher Burton
A light gray fabric pattern with faded vertical stripes.
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
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Adapted heavily from a JPG that was uploaded to Pixabay by Viscious-Speed.
Source Firkin
Dark squares with some virus-looking dots in the grid.
Source Hugo Loning
Seamless SVG vector and JPG backgrounds with faded diagonal stripes. The colors are editable.
Source V. Hartikainen
Kaleidoscope Prismatic Abstract No Background
Source GDJ
A hint of orange color, and some crossed and embossed lines.
Source Adam Anlauf
A car pattern?! Can it be subtle? I say yes!
Source Radosław Rzepecki
Floral patterns might not be the hottest thing right now, but you never know when you need it!
Source Lauren
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
Abstract Tiled Background Extended 8
Source GDJ
Derived from a drawing in 'The Murmur of the Shells', Samuel Cowen, 1879.
Source Firkin
Utilising some flowers from Almeidah. To get the unit tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
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