This site calls it basket check.

Take a look at American Restoration tile. MFG of all and any historic reproduction tiles.

Thank you. It is so satisfying to see that they still make these basket check tiles. At $75 sq ft it also may be the only thing that makes me thankful for how small my bathroom is!

As itty bitty tiles, they will all be pretty slip resistant just from the grout lines.

If the bathroom is small enough to install each tile separately, Daltile (and probably others) has 2x1 tiles but they probably aren't sheeted in that pattern.

Daltile also lets you order custom patterns (https://www.daltile.com/mosaic-tool). Not as cheap as their stock tiles, but I imagine less than $50/sf if they have a color you like. Not sure if they offer a basket weave on the website (I do see a lattice weave, which is similar) but they certainly make the tiles to create that pattern so you may be able to call to request it if it's not in the visualizer.

Another site to check is www.heritagetile.com

Great. I've written to both Daltile and Heritage and will post their quotes here in case it is useful to others. It seems Heritage mosaics are not manufactured in the USA, which is likely why at first glance their pricing seems to be around $22/sq foot instead of the $50-$75/sq ft, which are made in Arkansas and Minnisota.

It appears to be a basket weave/check pattern as others have mentioned.

Crossville Tile, Arizona Tile, & Emser Tile used to have a basket weave option, but we are unsure if it is still available.

If you can't find a tile you like that comes in a sheet, you can always see if you can go with a larger format tile and have your tile installer lay it out in this particular pattern. Ceramic tile and porcelain work well in a bathroom. Marble is naturally slippery when wet, so if you are looking for non-slip, marble is not the direction you want. Some tile mosaics come in a natural stone as well with a bit of texture and can potentially help with slipping.

Funny how the smallest things stick in your mind -- that's the tile that was on the floors (and walls) of my elementary school bathroom.

For those prices, I'd look around. It doesn't seem to be anything super-difficult to find.

Mrs Pete - I love that you remember this from your elementary school. I grew up in the 70s and we had a thick wall to wall shag rug in our bathroom, but when you peeled it back, this tile pattern was underneath. The house was built in the 1920s. I wonder why some tile patterns have endured and others not? All kind of hex and basket weaves are still around, but not so much this basket check. I think it is a bit more handsome and masculine of a design, which I like.

I have a 1940s bathroom with unglazed porcelain small hex on the floor. It is not slippery when wet. American Restoration Tile still makes floor mosaics in unglazed porcelain, I believe, with square edges on each tile. The surface is a bit uneven and gets a patina over time, but isn't smooth. Many people mistake our floor for marble, but it isn't. I think that's what you'd want if you are concerned about slips, or a stone, not a glazed tile. The type of small mosaic that many stores sell now days is glazed, and has a rounded edge on each of the tiles, and so the surface is much more slippery when wet. Good luck with your project!