Love Blue indeed attached great example of general definition what is a "hoarding",
which generally means to accumulate large amounts of whatever for whatever reason.
For example, gathering and keeping dry foods or canned foods in large quantities indefinitely in case of disaster
could be characterized as 'hoarding'.
A hamster is a typical animal food hoarder, or a squirrel 
indeed a lot of people do some type of hoarding, but the abnormal amounts some people do like the lady OP writes about
is not the same type of innocent hoarding - but is a mental disorder type of hoarding. that is a difference.
Fuzzy