The phrase "pack rat" refers to a person who keeps and hoards a lot of things, even if they are not useful or valuable.
Sentences with «pack rat»
I recall my friend being a fairly accomplished pack rat and unable to discard her growing children's library of early readers and baby furniture. (moneysense.ca)
It is thought that heavy storms left standing water that was contaminated by pack rats. (drnelsonsveterinaryblog.com)