Stumbled across these black, finger-like things poking out of the mulch in my backyard. They are hard and creepy. Does anyone know what this is?

If their presence is undesirable for aesthetic reasons, you can gently remove them, ensuring that you also remove any decaying wood substrates to prevent regrowth.
8. Safe Removal and Disposal Tips for Homeowners
To safely remove Dead Man’s Fingers, wear gloves to protect your hands from any potential irritants. Gently pull the fruiting bodies from the ground, ensuring that you also remove any underlying decaying wood.
Dispose of the fungi in a compost bin or yard waste container. Avoid discarding them in natural areas where they might spread unless you wish to encourage their growth in a different location for decomposition purposes.
9. Can You Prevent Dead Man’s Fingers From Coming Back?