When I was at MGM, the park that I first started collecting at, a CM saw me getting the pennies and she wrote down the stores that there in. At MK I went to the Town Hall and one of the ladies circled the locations for me. So just ask at the parks "Town Hall" type place. Also you can go up to a cashier and trade in dirty pennies for shiny ones. If you cant do that you can use an eraser to clean them off. Also they now have 100th anniversary quarter presses, the book for those tell you the locations. There are also penny presses at Downtown Disney. They are the old hand crank style, so go slowly so you dont smush it.