If my cousin lived here rent free she moved out over 3 months ago and left her clothes behind, can I throw them out?

Before you throw away your cousin's clothing that she left behind, I would write her a letter giving her an opportunity to pick up the items by a set date. For example, by July 15, 2012.

If the clothes are worth less than $300.00 collectively and July 15, 2012 comes and goes without the clothes being picked up, you can dispose of the clothing anyway you desire.