Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
From a drawing in 'Navigations de Alouys de Cademoste.-La Navigation du Capitaine Pierre Sintre', Alvise da ca da Mosto, 1895.
Source Firkin
Another fairly simple design drawn in Paint.net and vectorized in Inkscape.
Source Firkin
From a drawing in 'A Guide to the Guildhall of the City of London', John Baddeley, 1898.
Source Firkin
A seamless pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Derived from a design in 'Storia del Palazzo Vecchio in Firenze', Aurelio Gotti, 1889.
Source Firkin
From a drawing in 'A Life Interest', Mrs Alexander, 1888.
Source Firkin
It almost looks a bit blurry, but then again, so are fishes.
Source Petr Šulc
Someone was asking about how to achieve a fur pattern at #inkscape irc so tried to make a filter on it. Flood filled fractal noises rigged together. May someone find a good use for these.
Source Lazur URH
A seamless texture of an abstract wall colored in shades of light orange brown.
Source V. Hartikainen
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
An alternative colour scheme for the original background.
Source Firkin
From a drawing in 'Friend or Fortune? The story of a strange year', Robert Overton, 1897.
Source Firkin
A seamless chequerboard pattern formed from a tile that can be had in Inkscape by selecting the rectangle and using shift+alt+i. Alternative colour scheme.
Source Firkin
A seamless pattern the starting point for which was a 'rainbow twist' texture in Paint.net.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Got some felt in my mailbox today, so I scanned it for you to use.
Source Atle Mo
Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
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