Actually, cross hybridization has successfully been done before with mushroom species. Not p. cubensis though.
A strain of a particular species is "two compatible hyphae coming together to exchange genetic information" (-source: shroomery). "When monokaryotic mycelium meets a compatible hyphae from another spore, they exchange information and the cell lines become dikaryotic, meaning two or more nuclei per cell" (source: Marc Keith <RogerRabbit>

. The monokaryotic mycelium is the fluffy, whispy growth you see after first inoculating jars. The dikaryotic mycelium is faster growing and is the thick, white mycelia we look for in our grain spawn or PF-cakes.
No, growing shrooms doesn't smell. The only smell detectable is an earthy smell just like fresh mushrooms at the grocery store; pleasant if even detectable.
Cakes are good, but if you have a pressure cooker than cooking up grain jars or bags and spawning those to 6quart plastic trays along with a good bulk substrate is BETTER. For p cubensis I like to do 6quart trays of organic rye berries spawned to Coco-Coir (or Horse Manure), Vermiculite, Gypsum (calcium sulfate), Composted Chicken Manure (3%-5%). I would put these trays in either a "shotgun terrarium" or a small greenhouse setup (greenhouse setup also known as "martha-tek"

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If you need to be "stealthy" the best route is to forget growing mushrooms for the time being and instead purchase a pressure cooker and cultivate sclerotia. The following commercially available "strains" produce sclerotia: "ATL#7" is psilocybe galindoi. "A", "B", and "Jalisco" are strains of psilocybe mexicana. And "tampanensis" refers, of course, to psilocybe tampanensis. And all of them are classified within the section Mexicanae. Like all cubes are Cubensae. I recommend the popular "strain A" p mexicana, as do many others who have cultivated it. I never got to try jalisco or tampanensis because I wrecked the cultures, grrrr.
All you need to cultivate sclerotia is a pressure cooker, quart jars, and grain spawn. I also highly, highly recommend adding the 50/50 water/coffee soak to the grains and adding a pinch of gypsum (calcium sulfate) to the jars. A little light should be provided from either a window or a simple CFL bulb in the 6,500 kelvin temperature range. Sclerotia is more stealthy and easier to cultivate than cubensis even though cubensis is the beginner species for cultivators. Workman and Rogerrabbit over on the shroomery are responisble for much of what we now know about new methods in sclerotia cultivation.
arrive without traveling.