Mishnah Uktzin 3:3: The carrion of an impure [i.e. non-kosher] beast in all places, and the carrion of a pure [i.e. kosher] fowl in villages, require intentional thought but do not require being primed [to be rendered impure]. The carrion of a pure beast in all places, and the carrion of pure fowl and [forbidden] fat in the marketplaces, do not require intentional thought nor being primed [for impurity]. Rabbi Shimon says: even [the carrion of] a camel, a rabbit, a hare, or a pig [also require neither intentional thought nor being primed].

נִבְלַת בְּהֵמָה טְמֵאָה בְּכָל מָקוֹם וְנִבְלַת הָעוֹף הַטָּהוֹר בַּכְּפָרִים, צְרִיכִין מַחֲשָׁבָה וְאֵינָן צְרִיכִין הֶכְשֵׁר. נִבְלַת בְּהֵמָה טְהוֹרָה בְּכָל מָקוֹם, וְנִבְלַת הָעוֹף הַטָּהוֹר וְהַחֵלֶב בַּשְּׁוָקִים, אֵינָן צְרִיכִין מַחֲשָׁבָה וְלֹא הֶכְשֵׁר. רַבִּי שִׁמְעוֹן אוֹמֵר, אַף הַגָּמָל וְהָאַרְנֶבֶת וְהַשָּׁפָן וְהַחֲזִיר:

Mishnah Uktzin 3:4: The dill stalk, once it has given its flavor to a cooked dish, is no longer subject to [the requirement of separating] terumah [a portion of a crop given to a priest which becomes designated upon separation, and can only be consumed by priests or their household], and it cannot be rendered impure with the impurity of foods. The sprouting branches of hawthorn, and of garden-cress, and leaves of wild arum cannot be rendered impure with the impurity of foods until they are sweetened [to remove their bitterness]. Rabbi Shimon says: so too even regarding those [leaves] of the bitter-apple.

הַשֶּׁבֶת, מִשֶּׁנָּתַן טַעְמוֹ בַּקְּדֵרָה, אֵין בּוֹ מִשּׁוּם תְּרוּמָה, וְאֵינוֹ מִטַּמֵּא טֻמְאַת אֳכָלִים. לוּלְבֵי זְרָדִים וְשֶׁל עֲדָל וַעֲלֵי הַלּוּף הַשּׁוֹטֶה, אֵינָן מִטַּמְּאִין טֻמְאַת אֳכָלִים עַד שֶׁיִּמְתֹּקוּ. רַבִּי שִׁמְעוֹן אוֹמֵר, אַף שֶׁל פַּקּוּעוֹת כַּיּוֹצֵא בָהֶם: