there is collections button in sims inventory that shows all collectibles that at some point have been in your inventory/ have been discovered and they are also categorized by collection
I do feel we lack reasonable displays for collection rooms though because i keep having to invent my own with moo and stacked tables
and for storage i usually use boxes that came with eco or icya chest that came with university
(id use other prettier chests but the box and icya things are only ones with separated inventories which is sad but oh well)
you can also size those down to mini size so you just have small box full of stuff
+ you can label them so you know what collectables are in what box
even better you can then put those boxes to household inventory or sims inventory and tada collectibles neatly put away until you need them
as for usefulness of these items well i guess its mostly useless but fun looking items but i don't mind
in fact idk what kind of personality traits having lots of rocks should even give you in first place but :/
i guess i would love to make jewellery and such out of collectibles though that sounds cute
