Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
From a drawing in 'Picturesque New Guinea', J Lindt, 1887.
Source Firkin
This seamless background image should look nice on websites. It has a dark blue gray texture with vertical stripes, it tiles seamlessly and, like all of the background images here, it's free. So, if you like it, take it!
Source V. Hartikainen
White handmade paper pattern with small bumps.
Source Marquis
This was formed by distorting an image of a background on Pixabay.
Source Firkin
From a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
A free seamless background pattern for use on websites.
Source V. Hartikainen
It’s like Shine Dotted’s sister, only rotated 45 degrees.
Source mediumidee
From an image on opengameart.org shared by rubberduck.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
Original seamless pattern with an Inkscape filter.
Source Firkin