Could I have paid for the envelope with stamps?

So, I went to the post office today.
I don’t do this often so I don’t know much about mailing things.
I had a bunch of stamps with me because I didnt know how much it would cost me.
I needed a 6×9 bubble mailer so I got one from the many different mailers they have in there.
When I got up to the clerk she said she had to charge me for the envelope and I didnt know if I could have paid for it with the stamps I had. The postage was 4 stamps and I paid for the envelope with debit.

I should have asked her if I could have paid for the envelope with the stamps…..

Anyways,

Could I have paid for the envelope by placing extra postage on it?