Q. These odd things grow in my back yard from time to time and I was wondering what they are. Do you know? A. Try looking at this page on my blog.  Puffballs  I think they look like one of the puffballs that sits below ground. Fleshy, but they open up and look kind of disgusting. If this is it (hard to tell from the pic) then this should explain most of what you want to know. There is a rather complicated discussion about these living things online at several locations. Here is one by the self proclaimed “mushroom expert”. Puffballs from the expert Mushrooms growing in the wood mulch at the orchard after a rain. They are working on breaking down the wood mulch and recycling nutrients into the soil They are a mushroom and of course, like all mushrooms, feed off of dead, decaying organic matter rotting underground or on the soil surface. They are a fungal organism, a good one, most in the mushroom category called basidiomycete. They are decomposers, one of a many of different types of decomposers that aid in breaking down complicated, formerly living things, into much simpler components. They aid in enriching the soil in this process.    Underground mushroom, most likely a type of puffball called a peziza The spores or “seeds” of the mushroom begin growing with the right environment and food source. This includes enough moisture for growth and survival. In the desert the growth of these organisms frequently coincide with rain and warmer weather or some sort of irrigation presence. Germination of the spore leads to the spread of microscopic “webbing” or mycelium that acts much the same way that higher plants use roots, rhizomes and stolons. As this fungal organism matures most will develop some way to propagate itself in a way that is much more efficient over longer distances than developing the “webbing”.  Mushroom sexual stage, the one we recognize and draws our attention They develop a “sexual” stage (usually some sort of fleshy organ that can be somewhat similar in appearance to the mushrooms we buy in the store). These can appear to be like round balls growing on the surface of the soil (puffballs) or round balls below the surface. Each type has its own characteristic form or shape that helps us categorize them. Some mushrooms don’t have a form we can easily recognize but the sexual stage is what draws our attention like this slime mold that I get questions about every year. Again, usually after a rain during cooler weather. Slime mold, looks like “vomit” but can be easily destroyed with a rake and a stream of water I have had reports that dogs will eat these, usually resulting in the dog throwing up and having a sore tummy for awhile but seldom serious. Check with your veterinarian.