The edges of all the red objects line up either vertically or horizontally, but it doesn't appear so. Made from a square tile that can be got by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Triangular Background Design Mark II 5
Source GDJ
Continuing the geometric trend, here is one more.
Source Mike Warner
Remixed from an image on Pixabay, the original having been uploaded by darkmoon1968.
Source Firkin
Here I have tried to create something that would look like maple wood. Not sure how well it's turned out, but at least it looks like wood.
Source V. Hartikainen
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ
Zero CC tileable hard cover green book, scanned and made by me. CC0
Source Sojan Janso
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
People seem to enjoy dark patterns, so here is one with some circles.
Source Atle Mo
One can never have too few rice paper patterns, so here is one more.
Source Atle Mo
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Geometric Pattern Background 2 No Black
Source GDJ
Subtle scratches on a light gray background.
Source Andrey Ovcharov
This is the third pattern called Dark Denim, but hey, we all love them!
Source Brandon Jacoby
A bit strange this one, but nice at the same time.
Source Diogo Silva
I guess this one is inspired by an office. A dark office.
Source Andrés Rigo.
Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
A seamless pattern formed from miutopia's cakes on a tablecloth.
Source Firkin
Prismatic Geometric Pattern Background
Source GDJ
Derived from an image that was uploaded to Pixabay by starchim01
Source Firkin
This is the remix of "Background pattern 115" uploaded by "Firkin".Thanks.
Source Yamachem
To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Abstract Line Art Pattern Background 2
Source GDJ
There are quite a few grid patterns, but this one is a super tiny grid with some dust for good measure.
Source Dominik Kiss
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin