The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
The image is a design of blue glass.How about using it as background image?
Source Yamachem
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
Remixed from a vector adapted from a jpg on Pixabay. The tile this is constructed from can be had by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Classic vertical lines, in all its subtlety.
Source Cody L
Formed from a tile based on a drawing from 'Viaggi d'un artista nell'America Meridionale', Guido Boggiani, 1895.
Source Firkin
More in the paper realm, this time with fibers.
Source Jorge Fuentes