I am trying to create a basic menu that checks to see if the variable entered matches a defined variable. If the variable is defined get the data of the defined variable.
You'll need to use locals()[Choose_Item] if you want to choose a variable whose name is what the user produced.
locals()[Choose_Item]
A more conventional way to do this, though, is to use a dictionary:
items = { 'Item1': 'bill', 'Item2': 'cows', 'Item3': 'abcdef', }
... and then the value you want is items[Choose_Item].
items[Choose_Item]