collection class inheritance

Question

    First of all I am very new to c#. I am in a class, and I am dealing with a project where I have to keep track of many items that are similar using a collection class. The dilema arises that there are 2 types of items but they are very similar. I would like (I am almost sure this is possible) to have one collection class that is inherited by 2 different collection classes. I want to add the items using the child class. Based on the object type I am trying to add, it should be able to hold the proper information. I know I have done similar things using form inheriteance.