best luck we've had yet with getting shrooms to attach is to turn them loose in a low flow area in a pile of pea sized gravel, rubble, or shells... once they decide to attach then superglue the rubble or whatever to where we want them. Depending on where you put them in the tank sometimes they just bail from thier new home again, sometimes they stay put. They end up in the oddest of places sometimes...but as Rob suggested the input of a powerhead is as likely as anyplace for them to end up