A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
Derived from a drawing in 'Historiske Afhandlinger', Adolf Jorgensen, 1898.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
From a drawing in 'Gately's World's Progress', Charles Beale, 1886.
Source Firkin
From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
One more sharp little tile for you. Subtle circles this time.
Source Blunia
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
Zero CC tileable brick texture, photographed and made by me. CC0
Source Sojan Janso
Similar to original, but without gaps in between the arrows. This seamless pattern was created from a rectangular tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
A seamless pattern formed from a square tile. The tile can be retrieved by selecting the rectangle in Inkscape and using shift-alt-I.
Source Firkin
Inspired by a drawing in 'Poems', James Smith, 1881.
Source Firkin
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
A monochrome pattern from a tile that can be had by selecting the rectangle in Inkscaope and using shift+alt+i
Source Firkin
Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
This is a remix of "blue wave-seigaiha".I hope this subtle color version of Seigaiha would be suitable for background .
Source Yamachem
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle 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
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
I love the movie Pineapple Express, and I’m also liking this Pineapple right here.
Source Audee Mirza
A playful triangle pattern with different shades of gray.
Source Dimitrie Hoekstra
Derived from a PNG that was uploaded to Pixabay by nutkitten
Source Firkin