I know there is one here already, but this is sexy!
Source Gjermund Gustavsen
Sharp but soft triangles in light shades of gray.
Source Pixeden
A seamless background drawn in Paint.net and vectorised with Vector Magic. The starting point was a photograph of drinking straws from Pixabay.
Source Firkin
Prismatic Chevrons Pattern 5 With Background
Source GDJ
The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Prismatic Isometric Cube Extra Pattern No Background
Source GDJ
"Beige Stone", Tileable Texture.
Source V. Hartikainen
Prismatic Groovy Concentric Background No Black
Source GDJ
And some more testing, this time with Seamless Studio. It’s Robots FFS!
Source Seamless Studio
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Alternative colour scheme for the original floral pattern.
Source Firkin
Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
I love the movie Pineapple Express, and I’m also liking this Pineapple right here.
Source Audee Mirza
Formed by distorting a JPG from PublicDomainPictures
Source Firkin
You know I love paper patterns. Here is one from Stephen. Say thank you!
Source Stephen Gilbert
Prismatic Abstract Background Design No Black
Source GDJ
Remixed from a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
White little knobs, coming in at 10x10px. Sweet!
Source Amos
Same classic 45-degree pattern, dark version.
Source Luke McDonald
Here is a new seamless wood texture for using as blog or website backgrounds.
Source V. Hartikainen
That’s what it is, a dark dot. Or sort of carbon looking.
Source Tsvetelin Nikolov
A seamless textured paper for backgrounds. Colored in pale orange hues.
Source V. Hartikainen
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen
Derived from an image that was uploaded to Pixabay by Darkmoon1968
Source Firkin