A comeback for you: the popular Escheresque, now in black.
Source Patten
The basic shapes never get old. Simple triangle pattern.
Source Atle Mo
The name tells you it has curves. Oh yes, it does!
Source Peter Chon
Prismatic Groovy Concentric Background 5 No Black
Source GDJ
A seamless paper background colored in pale yellow.
Source V. Hartikainen
Prismatic Hypnotic Pattern No Background
Source GDJ
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
Colour version of the original pattern.
Source Firkin
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
Remixed from a drawing in 'A Girl in Ten Thousand', Elizabeth Meade, 1896.
Source Firkin
From a drawing in 'Les Chroniqueurs de l'Histoire de France depuis les origines jusqu'au XVIe siècle', Henriette Witt, 1884.
Source Firkin
ZeroCC tileable stone texture, edited from pixabay. CC0
Source Sojan Janso
With a name this awesome, how can I go wrong?
Source Nikolay Boltachev
A background pattern inspired by designs seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Background formed from the original with an emboss effect
Source GDJ
A free grid paper background pattern for using on web sites.
Source V. Hartikainen
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
Remixed from a drawing in 'The March of Loyalty', Letitia MacClintock, 1884.
Source Firkin
A brown seamless wood texture in a form of stripe pattern. The result has turned out pretty well, in my opinion.
Source V. Hartikainen
Number 1 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
Not so subtle. These tileable wood patterns are very useful.
Source Elemis
Zero CC tileable yellow craft paper; scanned and made by me. CC0
Source Sojan Janso
Some rectangles, a bit of dust and grunge, plus a hint of concrete.
Source Atle Mo