pack rat

a pack rat (someone who collects and stores things that they do not really need; who has lots of things, especially junk; someone who does not throw anything away) — барахольщик, барахольщица, плюшкин

Example 1: As a child, I was a pack rat, saving every little piece of insignificant paper that I thought might be important when I grew up.

Example 2: Aunt Lucy is such a pack rat. Her closets are all filled with old junk. — ...такая барахольщица — все шкафы забиты всяким старым хламом. (NTC's)

Example 3: She used to be a pack rat, but now she regularly has yard sales to get rid of unnecessary things. — Это она раньше была барахольщицей, а сейчас регулярнго устраиваете распродажи, чтобы избавиться от ненужного хлама.

Example 4: Melinda is such a pack rat. Have you seen her garage? It’s a disaster! (englishbaby.com)

a hoarder (someone who keeps junk; someone who hates throwing stuff away; a person who accumulates things and hides them away for future use) — барахольщик, барахольщица

Example: My brother is such a hoarder, you can hardly walk around in his house because there's so much stuff everywhere. (EB)

a magpie (someone who collects things that have been discarded by others)

a scavenger

Related vocabulary
БЕСПОРЯДОК
clutter (collection of things, unorganized group of objects)

Example: There is so much clutter in this house! I can’t stand it! We have to clean it all up immediately. (EB)
.....I hate clutter. I don’t need any more decorations or new knick-knacks for my home.

_______ВЕЩИ (ненужные), БЕЗДЕЛУШКИ, СУВЕНИРЫ, РЕЛИКВИИ_______

a knick-knack Also, a nick·nack
(a small cheap object used as a decoration; a small object used for decoration instead of function; an ornamental trinket or gimcrack; a bit of bric-a-brac)

Examples: .... ... (

bric-a-brac ({pronounced /ˈbrɪkəˌbræk/} {used with a singular or plural verb}
(miscellaneous small articles collected for their antiquarian, sentimental, decorative, or other interest)

a tchotchke {pronounced /ˈtʃɒtʃki/} (a knick-knack; a small object used for decoration instead of function; a small piece of worthless crap, a decorative knick-knack with little or no purpose)

Examples:
.... My grandmother’s house is full of tchotchkes.
(EB)
....a bedroom with polka-dot curtains, flowery wallpaper, and shelves cluttered with tchotchkes from a lifetime of vacations (merriam-webster.com)
..... Tchotckes, are in a sense, a symbol of consumerism. They have no actual purpose, aside from looking nice (or being hilarious.) There is a physical need to touch a knick knack when you see it on a shelf.

keepsakes (souvenirs; things from the past

Examples:
.... Because my family lost everything when our house burned down, I don’t have any keepsakes from my childhood.
(EB)

heirloom (item that a family keeps for generations)

Examples:
..... My great grandfather’s rifle is a family heirloom. We keep it mounted on our wall.
(EB)

a figurine
a figurine your grandmother would have next to her crystal candy bowl.

I love a good knick-knack. A little tchotchke. A lot of the ones that I have in my own home are actually hand-me-downs from my grandmother, and so they’re family items. I might call them family heirlooms. But I just love little keepsakes, just little things to really give your house some personality. (englishbaby.com)

Syn.
...bauble, gaud, gewgaw (also geegaw), gimcrack, kickshaw, novelty, ornamental, tchotchke, trinket.