The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Remixed from a drawing in 'An Index to Deering's Nottinghamia Vetus et Nova', Rupert Chicken, 1899. The unit tile can be had by selecting the rectangle in Inkscape and using 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 tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A classic dark tile for a bit of vintage darkness.
Source Listvetra
Oh yes, it happened! A pattern in full color.
Source Atle Mo
Prismatic Geometric Pattern Background
Source GDJ
Prismatic Abstract Geometric Background 5
Source GDJ
Retro Circles Background 7 No Black
Source GDJ
The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Prismatic Curved Diamond Pattern 7 No Background
Source GDJ
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
A topographic map like this has actually been requested a few times, so here you go!
Source Sam Feyaerts
A seamless pale yellow paper background with a pattern of animal tracks.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
Heavily remixed from a drawing in 'Barbara Leybourne; a story of eighty years ago', Sarah Hamer, 1889.
Source Firkin
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin