Okay, went to the beach today with my sons and collected a 5 gallon bucket full of various sized rocks from the beach. It was fairly mild weather, about 30 F, so we stayed longer than expected.
I put about 1/3 the rocks in a very large pasta pot, and I'm boiling them now. I dont really have room in the current 29G for all these rocks, but I plan on starting a 55G in the next few months in my office, and these will come in handy.
Thanks for into info in regards to "cooking" the rocks, I'll post some pics if I ever get them into a tank.