Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
Adapted from an image that was uploaded to Pixabay by Anerma.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
A seamless pattern based on a tile that can be achieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
Prismatic Geometric Pattern Variation 2 With Background
Source GDJ
Paper model of a tetrahedron. Modelo de papel de um tetraedro.
Source laobc
Could remind you a bit of those squares in Super Mario Bros, yeh?
Source Jeff Wall
Seamless Background For Websites. It has a texture similar to cork-board.
Source V. Hartikainen
Light and tiny, just the way you like it.
Source Rohit Arun Rao