Sparty, I have heard numerous reports of people literally throwing a shroom in a blender, chopping them up and spreading the remains around the tank as a means to spread shrooms. They are just that hardy. Cut any little piece of and secure it to some substrate and in all likelyhood it'll regrow. One method I use for progogating my shrooms is to chop the top clean off and dice it like a pizza. I'll get between 4 to 8 frags depending on the size of the cap I cut off. Now as with all corals, when you slice them/cut them or whatever, there is a chance of the coral getting a brown jelly infection and simple melting away to nothing. If this happens get the infected out and in the trash quickly. Brown jelly can spread around a tank like a bad virus. I have one hairy musrhoom that will brown jelly with every attempt to cut him, but yet he'll die off and 4 more will grow where he was. Then I have others that I want out of my tank and all the slicing and dicing and intentional attempts to kill it only make it grow and spread more. stubborn little shrooms.
If they are down in a hole, just cut the cap off, the foot will regrow a new cap in time and the cap will regrow a new foot in time. the foot is just the base of the shroom, lift up the cap to see it, or wait until the shroom is shriveled up some. You can even just slice the foot at an angle, don't cut if off, just a slice and it'll sprout another shroom from that cut. A nice way to thicken up a currently existing colony of shrooms.