The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
I have no idea what J Boo means by this name, but hey – it’s hot.
Source j Boo
Prismatic Geometric Tessellation Pattern 2 No Background
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
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
From a drawing in 'Bond Slaves. The story of a struggle.', Isabella Varley, 1893.
Source Firkin
A seamless pattern formed from a rectangular tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Dark wooden pattern, given the subtle treatment. based on texture from Cloaks. https://cloaks.deviantart.com
Source Atle Mo
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
Colourful background achieved with gradient fills.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A repeating background of thick textured paper. Actually, it turned out to look like something between a paper and fabric.
Source V. Hartikainen
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
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 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
The file was named striped lens, but hey – Translucent Fibres works too.
Source Angelica
After 1 comes 2, same but different. You get the idea.
Source Hendrik Lammers
Remixed from a drawing that was uploaded to Pixabay by DavidZydd
Source Firkin