Tosefta for Terumot 1:4

אֵין תּוֹרְמִין זֵיתִים עַל הַשֶּׁמֶן, וְלֹא עֲנָבִים עַל הַיָּיִן. וְאִם תָּרְמוּ, בֵּית שַׁמַּאי אוֹמְרִים, תְּרוּמַת עַצְמָן בָּהֶם. וּבֵית הִלֵּל אוֹמְרִים, אֵין תְּרוּמָתָן תְּרוּמָה:

One may not set aside <i>Terumah</i> from olives for oil, and not from grapes for wine. If one did set aside <i>Terumah</i> [from olives for oil or grapes for wine], the school of Shammai rules that their own <i>Terumah</i> [that was required of the grapes or wine] is among them, and the school of Hillel rules that one's <i>Terumah</i> is not [valid] <i>Terumah</i>.

Tosefta Terumot