What is this?
I'm new at gardening and I keep finding all kinds of scary things in my garden. Can you help me id this one? It popped up over night near my cucumbers.
Definitely fungal in origin. Mulch products can have fungal spores at the time of purchase or they can be introduced by animals and humans as one passes from an infected area to a new area. As the mulch decomposes the fungal spores feed on the nutrients released. If it is a significant problem, I would remove the mulch topping allowing the soil below to dry out, if this is an option, and hopefully killing off the spores. The apply new mulch that has been sterilized/heat treated. If the original fungal spores remain in the soil you problem will most likely recur. Excessive moisture encourages fungal growth.
A fungus which looks as though it is growing on forest bark chippings (which are probably damp?) A bit like mushrooms - but inedible - it will probably appear again almost overnight. Plenty of ventilation would help, but I would get rid if it is bark.