I am writing a little note to a person who returned my lost wallet. Is the following sentence grammatically correct? Please accept the cash enclosed herein, as a token of my gratitude. What is confusing me is whether there should be a comma before the phrase "as a token of my gratitude" My guess is that as the only cash enclosed is the cash offered as a gift, the information is non crucial, making the phrase non-restrictive clause, and therefore comma would be required.