They can be disgusting. There are times that I’ve called them the rats of the vegetable world — they are not vegetables. In our games we can use mushrooms as food.
What dungeon bound civilization hasn’t used fields of mushrooms for sustenance? Every time Drow, Dueger, Svirfneblin, and the rest raise shrooms. It’s part of the lore. Bioluminescent fungus and molds can be used for lighting as well.
These tropes are common in Dungeons & Dragons.
But you should also use mushrooms to build things. This is happening in the real world, but as bricks. Sure, that works in D&D. It makes a lot of sense for certain cultures.
Expand on that idea.
Who lives inside the shrooms like the Smurfs did. Or do your fey hide from the rain underneath a little cap.
What secret assassin group searches for a specific fungus for their signature poison? What apothecary makes a healing tisane out of mycelium and molds? Which street vendor took the meals of the underdark and turned them into handheld pastries stuffed with minced mushrooms and aged cheese making a name for themselves in the lighted world?
Everything you experience — eat, read, watch, listen to, encounter — can inspire you to add a little bit to your gameworld or character.