I would pluck out any wheats. You can look for a number of key and semi-key dates. Some other wheats to look out for are the 1922 no D and the 1955 Double Die. As for the Memorial Cents you can check for 1960 small date, 1970 S small date, 69 S, 70 S, 71, 72 S Double Die Obverse. 1983 Double Die Reverse, 1984 Double Ear, 1992 and 1992 D Close AM. 1995 Double Die obverse, 1998, 1999, and 2000 wide AM. On 2009 cents look for the Formative Years Cent with the extra thumb on Lincoln's hand. This is the cent with Lincoln as a youth sitting on a log. It depicts him as a log splitter reading a book.