Insuring packages with USPS

Insuring packages with USPS

I'm moving in the next few months and I wanted to ship some of my books and stuff to my mom so she can keep them for me until I settle down (if that ever happens). I'm going to insure the package before I send it, but my question is this: If the package is lost how will I fill out the claims form if I don't have receipts for any of my stuff? I tried looking this up on the USPS website but I couldn't find the answer. Have any of you gone through something like this? What winded up happening?
Ident help please

Ident help please

beware lots of clutter~

beware lots of clutter~

bird nest fern

bird nest fern

Plant ID

Plant ID

some of the lilies i spoke of yesterday :)

some of the lilies i spoke of yesterday :)

Orchids

Orchids