You'll need at least a 501(c)3 form and an offiical letter from the charity stating that any items donated to you will be used to raise money for said Counseling/Shelter Center.

When you reach out to different celebs you will need to send them these documents.

But needing the items by August... you are going to have trouble getting anything good in such a short notice.

Hello, My name is Penny Sailor, I'm from Monroe Michigan. On August 10.2013 I'm hosting a fundraiser at the Monroe Eagles . All proceeds go to Family Counseling and Shelter Services, for victims of Domestic Violence and Child Abuse. I was wondering how I would be able to get celebrities to donate memorabilia for raffles prizes. Does anyone have any suggestions? Thanks