Sounds like The Flower Pot Parasol, or "Spirit Cap" (latin name: Lecocoprinus Birnbaumii). Those yellow mushrooms are beautiful and harmless to the composting process, or your flowerpots, should you ever catch them growing there...as that's the most common place to appear. While the reports on it's actual toxicity are still out, they should be considered inedible because a small percentage of people have reported severe gastrointestinal upset from consuming them. But no, they won't harm your composting and in fact, they're helping speed it along by breaking down complex carbohydrates and cellulose into simpler sugars which will be further consumed when they, themselves begin to rot. Here is a link that might be useful: The Wikipedia link on Leucocoprinus Birnbaumii

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If you are going to go into production the easiest are among the many Oyster varieties; they are not as photogenic as domed fungii, yet taste is fine. You can grow them on waste cardboard - they degrade (eat) lignan, even sawdust. Turn over can be quick & even massive if you scale up. Most practical initially is to buy their prepared grain spawn & innoculate your fruiting medium. Oysters waft plenty of spores so find a place other than your favorite room. Shitake have become very well regarded & you can (again) buy their prepared innoculant. Dowel plugs are practical to stuff into a log & wait around for colonization. Buttons are what most people have seen. This is not a gourmet mushroom & usually their grow medium entails manure. Commercial buttton growing operations can not be competed with. (If you buy their spent medium as "mushroom compost" be aware it may be ridden with industry chemicals used to control crop contaminants.) You'll need to pay attention to temperatures when consider seasonal suitability of the different 'shrooms. Sorry, I do not sell mushroom spawn ( the first stage is desireable strain isolation, then fungii's mycelium proliferation & next transfer of culture to a substrate for mass proliferation of the mushroom "roots", called the spawn ) which you need to put among your bulk growing medium in order to harvest the fruiting bodies. I don't think the all included "kits" will give you a profit margin. Be informed that growing a mushroom from it's spores does not guarantee you will replicate it's characteristics. Aloha Medicinals, among others, has a superior mushroom strain bank. Don't expect any commercial enterprise's mycellium snippets to be cheap , they are proprietary.

OMG, Doug, you're beating all sorts of records here. When I was researching this for a Hoya talk I was giving in front of my gardening club, here are a few things I found: http://en.wikipedia.org/wiki/Hoya (THE most reliable source :-) ) says: "H. coriacea Blume has been known to have as many as 70 in an inflorescence". http://naturalb3auty.blogspot.com/2010/12/hoya-waxflower.html says: "Number of flowers per umbel varies from one (H. pauciflora Wight.) for 55 or even more." (Even more!, I tell ya, EVEN MORE!!!) So, those are the numbers I used. Next time I'll use your numbers. :-) By the way, I can't find the picture now, but Andrea Agillon in the Philippines once showed H. incrassata umbel on facebook where there were so many flowers that a lot of petals could not recurve - they were bumping into their neighbors. It looked like a mess, but quite an impressive mess. I see some of your petals also could not bend back here because of no elbow room. It did not look like she had 260 flowers on her umbel, although I may be wrong. It's hard to estimate these things.