A word of advice: Avoid those "ghost towns" that are no secret to the history books. You know, the types that are easy to find in the coffee table "Sunset Home & Garden Ghost Towns of the SW". Or tourist trap stuff in RV guide books, etc... Even if they contain mouth-watering pictures of ruins, walls, etc..., yet trust me: They've been worked to a frazzle. And avoid the obvious historic sensitive monument type ones too, lest someone "get their panties in a wad".
Instead, the best ones to find and hunt are the types are only found in obscure references. Ones that aren't easily readily seen in easy-to-find books. Short-lived little stage stops that went belly-up when RR's came through and took a different route. Or when the age of autos came and the little country cross-roads stops dried up. etc....
Maybe 30+ years ago you could walk right up to the easy-to-find ghost towns and find coins. But now, 30+ yrs. later, the obvious easy to find/access spots, have gotten hammered.