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
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
A simple bump filter made upon request at irc #inkscape at freenode. Made a screen capture of the making here: https://youtu.be/TGAWYKVLxQw
Source Lazur URH
I love these crisp, tiny, super subtle patterns.
Source Badhon Ebrahim
Vector version of a png that was uploaded to Pixabay by pencilparker
Source Firkin
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
A seamless dark leather-like background texture with diagonal lines that look like stitches.
Source V. Hartikainen
From a drawing in 'An Old Maid's Love. A Dutch tale told in English', Maarten Maartens, 1891.
Source Firkin
Dark blue concrete wall with some small dust spots.
Source Atle Mo
A dark one with geometric shapes and dotted lines.
Source Mohawk Studios
The classic notebook paper with horizontal stripes.
Source Are Sundnes
This is a seamless pattern of regular hexagon which has a honeycomb structure.
Source Yamachem
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
Based on several public domain drawings on Wikimedia Commons. This was formed from a rectangular tile. The tile can be accessed in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Old China with a modern twist, take two.
Source Adam Charlts
The tile this is based on can be retrieved by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Not strictly seamless in that opposite edges are not identical. But they do marry up to make an interesting pattern
Source Firkin
Prismatic Abstract Geometric Background 5
Source GDJ
A seamless pattern based on a square tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
Sometimes simple really is what you need, and this could fit you well.
Source Factorio.us Collective
Not sure if this is related to the Nami you get in Google image search, but hey, it’s nice!
Source Dertig Media
From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin