Hello,
I have a crusty old Morgan Silver Dollar with an upside-down 5 counter-stamped on the face of it. I was planning to get rid of it for cheap, but someone told me that counter stamps can sometimes carry some meaning/value if you can find the origin of it. I thought I would first post it on here to see if any might recognize it. Any help is appreciated, thanks! 

The premium usually comes from when a counter stamp is done my a company, business, or a specific person, not just a number.

First I ever seen its actually stamped into the metal?

Not heard of Morgan's being counterstamped

Look's like someone took a number stamp from shop class, circa 1949 and stamped it on a morgan. Just my guess. 

Really cray coin can be counterstamped, but large cents and small denominations are going to be the most common. I've seen them on half dimes before.