What do I have???

I hope someone can help me. I work at a bank and I see hundreds of coins pass in front of me everyday. The other day I noticed that in my penny stacker I had what I thought was a dime. It was smaller like a dime so I pulled it out. It was a 1944 Mercury Dime. When I laid it aside on my counter, I noticed that on the back of it was a wheat back penny. Since it came out of a penny roll to begin with, I bought it for a penny thinking that even if it is nothing, it only cost me a penny. Does anyone have any idea as to what this is? I hate to take it to someone who will charge me only to tell me that it's junk.

I also had a customer bring in 3 Walking Liberty Dollars (dated 1991, 1992, 1995). All three are stamped "1oz. Fine Silver" on the back. I had someone tell me they were not legal tender but I let the guy exchange them anyway. He also brought me 2 Walking Liverty Half dollars (both dated 1942). Can anyone tell me what they may be worth? I know that the better the condition, the higher the value. But again, I hate to take them to be graded and end up paying more than they are worth.

Thank you in advance for taking the time to help out a teller who obviously has WAY too much time on her hands.