The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
This could be a hippy vintage wallpaper.
Source Tileable Patterns
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A pattern formed from a squared tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Seamless Olive Green Web Background Image
Source V. Hartikainen
ZeroCC tileable moss texture, photographed and made by me. CC0
Source Sojan Janso
Dark Tile-able Grunge Texture. I think this texture can be classified as grunge. It's free and seamless, as always.
Source V. Hartikainen
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin
From a drawing in 'Two Women in the Klondike', Mary Hitchcock, 1899.
Source Firkin
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Remixed from a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
A free seamless background texture that looks like a brown stone wall.
Source V. Hartikainen
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A beautiful dark padded pattern, like an old classic sofa.
Source Chris Baldie
Not a flat you live inside, like in the UK – but a flat piece of cardboard.
Source Appleshadow
It looks very nice I think.
Source V. Hartikainen
Prismatic Chevrons Pattern 5 With Background
Source GDJ
Nicely executed tiling for an interesting pattern.
Source Ignasi Àvila Padró
Prismatic Polka Dots Mark II No Background
Source GDJ