Over at the wiki, the data for results of the two random drop circumstances - An Unprepossessing Mass and A Cache of Curiosities - are coming along well, but more data is needed! While Mass values in particular are relatively easy to check for completeness, it’s very possible that there are rarer successes missing for any given value. And there may yet be many Cache results unseen by editors.
Most of the Mass and Cache data has come from my own time farming Western Angler Crabs and Pirate Frigates, respectively, so it’s also possible that there are additional results that only drop from other sources (e.g. Mass values greater than 50, or monsters that have an even lower maximum Mass drop? more/fewer possible Cache results?)
So, if you’ve found something not already listed, please do chip in! And if you want to add something without dealing with the Wiki formatting, feel free to post it here - aside from the exact Mass value (which should be jotted down before you open the Mass), everything needed is on the same page where the actual loot is displayed. Just list the two lines in bold, and the exact loot - that’ll be enough for categorization.