No and none. And mailing something to yourself was never worth anything.
Under the previous U.S. patent law (anything filed before that portion of the AIA took effect in March 16, 2013), one could win a dispute with someone who filed earlier than you filed by showing you conceived of the invention before the other person and diligently went about reducing it to practice. This was called an inference proceeding. Many things could be used as evidence, but an "unopened" envelope you mailed to yourself was treated exactly as an unsubstantiated assertion by the inventor, meaning it was of no evidentiary value.
Of course you never filed anything so, even under the old patent rules, you had no priority to fight over. We are now a first-to-file country but due to the strange 1 year grace period of the AIA you could also think of it as first to publish, as long as you filed within a year and didn't go beyond the publication. You didn't file or publish or even effectively establish a date of conception.