Nah! I was just teasing him regarding keeping it under the lawn. I do keep a pile of black dirt out in the back corner of our place for filling planters, low spots in the lawn, etc... I had so much of it accumulated over the years that I ended up making a 2' high berm all the way across the back of our yard, about 150' long x 2' high x 4-5' wide. Funny how I never bring dirt to our place, but the pile grows each year. Lots of it comes from leaves being composted, yard waste, etc... what doesn't get used on the garden goes in the stock pile.
I think keeping it under a roof would keep the rain from leaching out some of the nutrients, although
*it may dry it out a tad.