Truma for a Yisrael (Eruvin 31a)

The Mishna on 31a says that a kohen can use truma for an eruv. The mishna though on daf 26b quotes that as a machlokes. The tanna kama says that even a Yisrael could use truma. Only Sumchus disagrees. This appears then to be a stam mishna like Sumchus - machlokes v'achar kach stam - implying that we should pasken like Sumchus. We don't and the Shiltei Giborim says that our Mishna doesn't mean that only a Kohen can use truma it's just using that as an example because they're the ones most likely to have truma.

Also, the mishna on 26b quotes another machlokes between an anonymous tanna (we'll call it Rabonnon) and R' Yehuda about a kikar in a beis hakvaros for a Kohen. The Rabonnon say that only if the kikar is in a beis hapras can a Kohen use it for his eruv but R' Yehuda says that even if it's in a beis hakvaros he can use it because it's still possible for the Kohen to get there. Rashi on daf 30b all the way at the bottom says that they both hold like Sumchus that it must be edible for that person and the only question is what's considered accesible. The top Tosafos on 27a argues with Rashi and says that the Rabonnon may really agree with the Tanna Kamma in the reisha that it doesn't have to be edible for that person. They say though that it does have to be accessible - because of a different rule of "hu b'makom echad v'eiruvo b'makom acheir."