Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
Prismatic Isometric Cube Wireframe Pattern No Background
Source GDJ
Background formed from the original with an emboss effect
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Derived from an image that was uploaded to Pixabay by mdmelo.
Source Firkin
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
A free seamless background image with abstract texture of green "curtain".
Source V. Hartikainen
Prismatic Geometric Tessellation Pattern 4 No Background
Source GDJ
Light gray pattern with an almost wall tile-like appearance.
Source Markus Tinner
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Dark, square, clean and tidy. What more can you ask for?
Source Jaromír Kavan
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
Prismatic Hypnotic 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
Just like your old suit, all striped and smooth.
Source Alex Berkowitz
Zerro CC tillable texture of stones photographed and made by me. CC0
Source Sojan Janso
Heavily remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin