Sure! Let's start with the obvious. What you are seeing are blocks of sawdust and wheat bran (substrate) in a humidity and temperature controlled grow tent. In this case, you are also seeing the fruit of a Lion's Mane mushroom. Hericium erinaceus is an interesting species. Instead of forming a standard stem (stipe) and cap, it forms dense balls that grow spines that resemble an actual lions mane. (Mature fruit picture in the link)

To start the grow, I take a few sterilized jars of partially cooked grain (rye berries, rice, millet or whatever) and inject a culture of mycelium. The mycelium will develop and spread at a fast rate and eventually fill the jar and cover all the grains. (The function of this is for a couple of reasons: It creates a lot of mycelium so it will colonize a less tasty substrate quicker; It gives the mycelium a nutrient rich environment to outpace growth of any other bacteria or unwanted spores that might be lurking in the grain.)

Quick tangent about the environment and grow conditions to set the context: Bacterial and fungal growth is highly competitive. By keeping the quantities of "good" mycelium higher in any environment at all stages of the grow, I can prevent the development and growth of anything else that is undesirable. Mycelium naturally produces metabolites that fight other infections and its excretion is how penicillin was discovered. Understanding this is also how I can transition from a lab-sterile environment (when working with spores or samples of mycelium) into a "normal" gardening environment where full sterilization is not needed.

When I start the grow, I load up a grow bag with a few pounds of substrate and then sterilize the bag in a pressure cooker for a few hours. After the bags cool down, I mix in a fully colonized jar of grain, seal the bag and put it in a warm area for 2-3 weeks. The mycelium spreads through the substrate and eventually it is ready to fruit.

By dropping the temperature a few degrees and cutting a hole in the bag, I can trigger the mycelium into fruiting. Fresh air, lower temperatures and higher humidity make the mycelium "think" it has gotten closer to the soil surface and that winter is coming soon. As a form of self-preservation, it forms its fruit in preparation to spread its spores. In this case, I will harvest the fruit in a day or so before it sporulates and becomes bitter. After this fruit is removed from the bag, it may produce 2-3 more fruit bodies before the substrate is fully consumed by the mycelium.

Basically, I am simulating a rotting tree and seasonal changes with the block of sawdust substrate and controlled environment.

Different mushrooms have different environments and substrates they prefer. If you look into my profile from the last day or so, I have posted some pictures of baby psilocybe cubensis mushrooms that are forming on a substrate of coco coir at warmer temperatures in a much cleaner environment. This particular species is a bit more vulnerable to infection from trichoderma which can overtake the "good" mushroom mycelium at an extremely rapid pace. (Trichoderma is great for gardens as it will choke out a ton of other bad fungal infections. It's also very common and you are probably inhaling a few spores of it as we type, depending on where you live. When an old loaf of bread molds and turns green, it is likely trichoderma and not penicillium chrysogenum that you are seeing.)

Would you like to know more?