In Yirmiyahu 2:3 there is a Mahari Kra that attempts to explain what the words "Reshit Tebu'ato" ("רֵאשִׁית תְּבוּאָתֹה") are regarding. One of the things he mentions were the three terumot. What are these terumot?
The Mahari Kara also says all three t'rumos are called "reshis". I think they're probably