A comeback for you: the popular Escheresque, now in black.
Source Patten
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Seamless Prismatic Geometric Pattern With Background
Source GDJ
Not even 1kb, but very stylish. Gray thin lines.
Source Struck Axiom
No, not the band but the pattern. Simple squares in gray tones, of course.
Source Atle Mo
From a drawing in 'At home', J. Sowerby, J. Crane and T. Frederick, 1881.
Source Firkin
Prepared mostly as a raster in Paint.net and vectorised.
Source Firkin
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin
Prismatic Polka Dots 3 No Background
Source GDJ
Nice little grid. Would work great as a base on top of some other patterns.
Source Arno Gregorian
On a large canvas you can see it tiling, but used on smaller areas, it’s beautiful.
Source Paul Phönixweiß
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
From a drawing in 'An Old Maid's Love. A Dutch tale told in English', Maarten Maartens, 1891.
Source Firkin
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
I’m guessing this is related to the Sony Vaio? It’s a nice pattern no matter where it’s from.
Source Zigzain
Super detailed 16×16 tile that forms a beautiful pattern of straws.
Source Pavel
Seamless tile drawn in Paint.net and vectorised in Vector Magic.
Source Firkin
Stefan is hard at work, this time with a funky pattern of squares.
Source Stefan Aleksić
Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
A textured blue background pattern with vertical stripes.
Source V. Hartikainen
Light honeycomb pattern made up of the classic hexagon shape.
Source Federica Pelzel