When I was getting cat food this last time, though, they had these cute little "grow your own" kits, so I bought one - mostly out of curiosity (it's just wheat, plain old standard every-day wheat). Plus the directions were simple enough - put the wheat on top of the (included) dirt, keep moist, give to cat when sprouts are four inches tall. So I did as directed.
Yesterday morning I noticed what appeared to be sprouting activity, some of the grains were tipped into different positions, or had moved a little. By mid-day there were little shoots poking up here and there. Now there's a miniature forest of little green spikes, so things seem to be coming along properly.
The scary part is the speed at which the stuff grows. I've got the container sitting in the kitchen, and every time I walk by it (every couple of hours or so) I swear the stuff has gotten another millimeter taller. I've seen stop-motion photography of plants growing, but it's kind of eerie to feel like if I stopped and sat there watching it, I could probably see it getting taller.
Suddenly all those "Day of the Triffids" type stories make a little more visceral sense.