Cleaning question?

I dug this a couple days ago and can't id it. I've cleaned it with soap and water and I'm able to make out some details (it appears to be a LIBERTY HEAD with six pointed stars around it on the front and on the back it has a wreath). I'm afraid to clean it with anything stronger because I was told if the coin is rare you will decrease the value by cleaning it. I thought about soaking it in olive oil but have leaned recently that olive oil can blacken it too much. I think the coin/token is silver but I'm really not sure. When I first pull it out of the ground I thought the coin had been through some kinda trauma accounting for its odd oval shape but as I cleaned it up I realized it was made like that because the detail on the coin corresponds with the shape. I've tried to reseach it but have come up empty, the only thing that comes close is some gold coins (in RED BOOK) from mid 1800's. I also was able to find some California gold coin/tokens from the gold rush era (in WORLD COINS) that looked like mine but none were oval although some were octagon. All the coins I've been able to find that has the same detail as mine (the LIBERTY HEAD with stars on the front and the wreath on the back) are gold and I think the one I have is silver or maybe brass/bronze so I have no idea what it is. I'm hoping someone here can help me with the IDing of this coin/token. Please if you know anything about this coin reply to my post or if you're not sure and just want to guess that can be a big help also! Anything is welcomed! I've attached some pictures of the token/coin and also of something that kinda looks like it from the RED BOOK. Also whats the best way to clean it?
Keep your coil to the soil,
HH