I'm wondering if there's a guide or something that gives a list of the past collectible collection choices? I've got some spare CSC to spend and was curious to see if this month's older collection might have something I want!

There's this SubetaLodge page that lists all the collectibles, hope that helps :)

There's this on-site guide: Guide to Monthly Collection Items + DPs but it's not updated with everything from last year. It should be fine if you're looking for the older collections, though.

Another option is to search up the month it is on SubetaLodge, that brings up all the presents from that month over the years. And then click in the item notes of the item to see all the items it contains.

ahh awesome! thank you both so much! :D