A Package of Identified Plants contains many consumables, vendor trash, and herbs.
It can also contain [Uncatalogued Species], which starts a new quest.
This item is rewarded from the quest  Plants of Zangarmarsh and the repeatable quest  Identify Plant Parts.
To complete the quests, turn in 10 [Unidentified Plant Parts] to Lauranna Thar'well at Cenarion Refuge. The quests also rewards 250 reputation with the Cenarion Expedition.
This item can contain:
And various Azeroth herbs.