Certified GKH Gardening Expert
This is the, aptly named, Dog-vomit fungus, or Fuligo septica.
They have reached the sporulation stage. This is quite the beneficial creature, though. They feed, strictly, on bacteria. Likely, they are present because your plant has a bacterial infection. This "fungus" is doing what it can to help you rid your plant of that infection. Treating with a fungicide will be a good idea, here.
This article will help: