What you have there is a Paneolus (or Stropharia, depending on which taxonomy you follow) species, but it's not a hallucinogenic one.
I'd guess it's one of the species known as "dung roundheads".
24 x 3W = 72W
50V x 630mA = 31.5W
I don't think Your power supply is going to be up to it. :(
Even assuming it can supply the full current at 100V, that's only 63W :(
Yep. Looks like stem borers. :(
They're the larvae of beetles or moths which tunnel into the middle of the stem and live there... generally speaking, they're not good for the plant.
Google "stem borer" for info & pix. ;)
Coco is definitely the easiest introduction to hydro... great results and damned simple. :)
You might also like to have a look at NFT systems if you're feeling a bit more adventurous.
I've been using a Dual Flow NFT system for a few years now, and I'm very happy with it. It can be used as an...
Difficult to tell from the pix, but I'd guess at coco coir or peat.. those are a couple af things used regularly over vermiculite to make the mushrooms pop their little heads up. :)
Either way, it's not likely to be anything toxic.. just "dirt" left over from the grow.
Have fun! ;)
I actually run a recirculating system these days, but I've done coco grows where I've let about 5-10% run off.
I suppose that equates to about a gallon for 6 plants in bigish pots.. not as much as I thought, actually. :)
I was running direct into a drain tube at the time, so I wasn't really...