It's too hot and dry to grow them outside here; they need to be cool and moist and preferably dark. I was going to put them in the downstairs bathroom that rarely gets used, but under the kitchen sink seemed more logical in my case since I can't store anything else there. You could grow them in a pantry or even under a bed if you put a plastic tray underneath. They're really simple -- I forgot about mine for about three weeks before they sprouted, and when I remembered, I just doused them with about two cups of water and they sprang right back.
The cabinet is damaged because the previous owners of our house let the pipes leak for ages, so the bottom is all warped and gross. I can't really use it for pots and pans without feeling like I have to wash them before I can use them, and I don't like to store my cleaning supplies down low with small kids in the house. Plus, there are so many pipes down there at odd angles (because the garbage disposal was retrofitted, and when they fixed the leaky pipes they did a shitty job of it) so nothing really fits.
So I installed a rack on the inside of each of the doors to keep plastic baggies and tinfoil and stuff in, to make the best of that vertical space. And I put a few layers of reclaimed cardboard in the bottom of the cabinet to level it out as best I could, and slid the mushroom log in under the pipework. It stays slightly cooler than the rest of the kitchen in the summertime because an A/C duct runs right underneath it, so that's good (since mushrooms grow best just a little below room temperature -- about 64F). I keep a spray bottle of water in there and give it a good misting about once a day, when I remember, which is probably only about 3/4 of the time. The kids love checking on the mushrooms with me; once they sprout, they can double in size overnight. It's pretty exciting.