About all I know about Marysvale is that it is a former mining town. Folks mined things like gold, silver, and uranium. My wife's grandfather actually mined the latter and you can still see the huge scar on the mountain to the North East of town. My own great-grandfather had several mine claims in the area and one of those became my grandfather's who did mine a bit of gold out of there but it wasn't enough to make it worth it. There are a few caches out there, there is also river rafting, 4-wheeling, and you must check out Big Rock Candy Mountain while you are there.
As far as caches go...there is a series out there called RMATV. It is a series of 10 caches and according to the owner the series is designed to be done in a day. As I don't know the area all that well my suggestion is to do a search using zip code 84750 and see what you might be able to do.