Should I negotiate my severance?

My manager said the package is final, but the letter gives me time to review. I have read a lot of threads here and could not find my exact situation. I do not want to leave money on the table. Did anyone negotiate and succeed?

An hour with an employment lawyer cost me a small fee and made me feel much safer about signing.

Read the release carefully. Mine included things I did not expect, like a non-compete.