several 426 Hemi's burried
Go digging, especially if you have access to a backhoe. Worst case scenario is you dig up a bunch of cast iron thats worth over $100 a ton at the scrap yard, best case is you dig up something really cool even if its not usable it would be a neat yard ornament. In this day and age when certain brackets and pullies cost over $100 you could probably net enough off of e bay to make it worthwhile. I was grading my parents yard once and went into this overgrown patch to smooth it out and caught the corner of something. Before my curiosity ran out I had dug up an entire Corvair and a 56 Ford.