The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
A repeating background for websites with a texture of black groove stripes.
Source V. Hartikainen
A free pink background pattern.
Source V. Hartikainen
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
To get the tile this is formed from select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
A tile-able background for websites with paper-like texture and a grid pattern layered on top of it.
Source V. Hartikainen
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless Prismatic Quadrilateral Line Art Pattern No Background
Source GDJ
Prismatic Abstract Background Design
Source GDJ
Remixed 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
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
The image depicts a seamless pattern of pine tree leaves.
Source Yamachem
This one is super crisp at 2X. Lined paper with some dust and scratches.
Source HQvectors
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
Bright gray tones with a hint of some metal surface.
Source Hendrik Lammers