Features:

Chicken of the Woods (Laetiporus sp.)¹ is a real-life edible sulfur-colored shelf fungus that grows on standing or fallen dead wood. It's described as having a chicken meat taste after cooked, giving it the name. It mainly grows on oak trees and doesn't require rain to fruit; but it has variants throughout the United States: mainly Laetiporus cincinnatus which has lighter orange hues and Laetiporus conifericola which grows on coniferous trees. It has a number of medicinal properties from anti-bacterial, anti-inflammatory, and anti-fungal. It's commonly used in stews and tinctures and is a choice for novice mushroom hunters due to its easy-to-spot nature and lack of poisonous look-a-likes.

An implementation of it in Minecraft would be shelf fungi having a rare chance to generate with fallen oak or spruce logs in forests. With a low chance for regeneration on oak or spruce logs exposed to moss or other mushrooms. The player can collect the mushroom to consume for minor saturation (item named "Chicken of the Woods" or "Chicken Fungus") as an early-game food source. Though it must be collected by shears as it's a delicate mushroom and cooked first or it'll give Hunger (it causes indigestion in real life). Combined with an Oxeye Daisy and a bowl it'll produce a Suspicious Stew with both Regeneration and Strength effects (like the real life tinctures people make with them).

(1: Chicken of the Woods)(2: The Wild Concept Art)

Lichen (Letharia vulpina)³ is a hybrid organism that functions as a low-level producer and nutrient recycler that grows on rocks and trees of forest from sea-level to the alpines and is classified as a biomonitor for how it helps determine the air quality around it, as it's very sensitive to air quality and gets its nutrients from the air. They're what help forests recover from cataclysmic events such as forest fires, though they've been recently losing out on the "fight" due to climate change and extreme wildfires.

An implementation of it in Minecraft would be for it spawn around or on charred logs in forests, with it having the rare chance to "heal" surrounding logs or grass by converting logs into moss or the log that came before it being charred, and the grass having a chance to spawn grass, mycelium, loam, podzol or fungi depending on the biome. Lichen already exists in the game, but not with this dynamic with forests. Players can also plant lichen nearby charred logs to help them heal recently burned forests. Serving as an in-game lesson about climate change and how their ecosystems function.

(3: Lichen On Bark)

Alternatives:

This would be an alternative to the concept art's fungi depicted above² and strikes a nice balance between aesthetics, uses and vanilla mechanics.

Additional info:

It's worth noting that the mod Plants&Junk⁴ has a similar implementation of shelf fungi, though it's aesthetic only and more strictly follows The Wild concept art above². Also the mod Spelunkery⁵ has its implementation of shelf mushrooms in the form of Conk Fungi, though it's also just aesthetics and serves as a wood replacement.

(4: Plants&Junk Shelf Fungi and Vines)(5: Spelunkery Conk Fungi)