Snap! It’s a pattern, and it’s not grayscale! Of course you can always change the color in Photoshop.
Source Atle Mo
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
Prismatic Curved Diamond Pattern 5 No Background
Source GDJ
From a drawing in 'Hyde Park from Domesday-Book to date', John Ashton, 1896.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
Prismatic Curved Diamond Pattern 8 No Background
Source GDJ
A dark gray, sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
A seamless pattern formed from a modified version of rwwgub's tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Seamless Prismatic Geometric Pattern With Background
Source GDJ
This white background pattern has a seamless grunge style texture. Here's a white grunge style background pattern. Use it as a tiled background image on web sites or for other purposes.
Source V. Hartikainen
From a drawing in 'Codogno e il suo territorio nella cronaca e nella storia'', Gio and Giarella Cairo, 1897.
Source Firkin
From a drawing in 'Line and form', Walter Crane, 1914.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
Seamless pattern the basic tile for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Remixed from an image that was uploaded to Pixabay by KirstenStar
Source Firkin
This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Psychedelic Geometric Background No Black
Source GDJ
Prismatic Groovy Concentric Background 2 No Black
Source GDJ
Background formed from the iconic plastic construction bricks that gave me endless hours of fun when I was a lad.
Source Firkin
The image depicts the Japanese Edo pattern called "seigaiha" or "青海波" meaning "blue -sea- wave".I hope it's suitable for the summer season.
Source Yamachem
8 by 8 pixels, and just what the title says.
Source pixilated