While I don't get them often, it's always nice to get a texture challenge submission. Since they're optional, they usually demonstrate the kind of focus and enthusiasm that comes with a student doing something of their own volition, rather than simply being told to. That isn't to say there aren't some issues I can address and help you out with, but it does generally mean that the student has put a lot of their own effort into it, and that also means that what I'm looking at is likely to be the best they can do right now.

Overall, I'm definitely seeing a great deal of attention to your reference - you're demonstrating excellent observational skills, as well as a lot of time and effort being put into the specific design of the marks you're putting down on the page. I'm not seeing much in the way of randomness, and there are some really awesome examples of shape design in cases like the rice grain texture. Really solid stuff there, and it shows that you're thinking about the way in which those forms sit in 3D space, holding a ton of very complex information in your mind, as you find the "right" shadow shape to put down.

The first major issue - and really the only one that really stands out - is to do with that solid black bar on the left side of your texture gradients. Through most of these, they're each a very clear, strongly delineated/separated black bar. But in the instructions (specifically those highlighted here) it does mention that this black bar serves an important purpose. It establishes the darkest and densest our texture gradient will get, and it is our responsibility to achieve a smooth transition from that black bar, to the white bar on the other side.

What we really want is to "lose" the right edge of the black bar - to be unable to identify where the bar ends and the texture "begins". Right now unfortunately you only have a few cases where you've done that, and in general you can definitely stand to really push the darker, denser side of the texture and expand just how far it stretches towards the middle of the gradient. This will allow a more gradual transition, rather than a sudden jump. The fish scales and the cake textures were definitely better in this regard, but even there, that darker area can be pushed much further to create an entirely seamless transition.

Now, it's very easy to end up feeling timid when you hit that point, but it is important to keep in mind that cast shadows are entirely within our control, and it can help to think of how the shadow of a sundial can be made very small and slight (like at high noon) or very long and deep (like at dusk or dawn) depending on the relationship between the spike of the sundial (in this case, which corresponds to each of our textural forms), and the position of the light source. This texture analysis exercise's layout actually leans into this as well - the light source is on the far right, so the far right of the gradient gets blasted out, but the far left is much farther away, and receives those light rays at a much lower angle, leading to longer, more stretched out shadows.

With that out of the way, the last thing I want to share isn't actually something that comes up in your texture work as an issue, but it's something I want to share anyway, as it may be helpful in general. It's this diagram about the role holes play in our textures, which I haven't yet integrated into the lesson material.

In essence, textures with prominent protruding forms - like bricks sticking out of a wall, or gravel on the ground - are pretty easy to make sense of, because the textural forms are the physical objects we can identify as being present. When we deal with textures that have more prominent use of negative space - grooves, gaps, cracks, holes, etc. - we continue to think of those named elements as being the textural forms, but that is not correct.

Rather, it's the walls and floors of those holes that are the textural forms, and the surfaces that receive those shadows. We may end up simply trying to fill in the holes, but that ends up being an oversimplification. Filling in the shapes of those holes doesn't cause us to think about the relationships between the different textural forms and the surfaces around them - we just fill them in and go about our day, and it's usually close enough to feel correct. But we've thought about them incorrectly in this manner, and left out little, subtle considerations that could make our textures more believable, and to help them convey a greater sense of tactile value to the viewer, showing them truly what it'd feel like to run their fingers over that surface.

So, be sure to keep that in mind. Again, it's not something that directly applies to any of your specific textures, but I suspect that it may help you better understand how to think about all your textures in general, and may help you achieve better results as you continue to practice these.

All in all though, you've done a great job and have clearly put your all into your work here. I'll go ahead and mark this challenge as complete, so keep up the excellent work.