Yes, Pam, the post office has lots of free envelopes (regular and padded) and boxes, especially for Priority Mail. And they do deliver it to you for free. It's easy to order them on-line.

Here is what they have (note all those that say "no charge"):
https://shop.usps.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10001&storeId=10052&categoryId=10000033&langId=-1&parent_category_rn=10000002&top=&sort=&viewAll=Y

One tip -- look into free Priority Mail "REGIONAL" boxes -- there are two for Regional rates "A", and two for Regional rates "B." This is a new thing I just learned about. They are flat rate boxes for regional zones. For example, the post office gives you a free flat rate regional box, say marked Region "A." You put whatever you want into the box (weight does not matter, unless it is a huge weight) and then look at the rate tables -- you pay according to the zone (distance from you), not weight. Table is below. (What is so good about the Regional Priority Mail "flat rate" boxes is that is that you save a lot for short distance mailings (i.e., to zones near you), as opposed to the Flat Rate boxes that are charged a really flat rate -- same rate to any distance or zone in the US.)

Robert