Bikkurim, Chapter 3, Mishnah 5. This mishnah deals with the birds that were brought along with the baskets of bikkurim and offered as sacrifices. This is a continuation of what we learned earlier - 'itur habikkurim', the adornment of the bikkurim: together with the baskets they would bring turtledoves or young pigeons, from among the types of birds offered in the Beis HaMikdash, and hang them on the sides of the baskets. They were careful not to place them on top of the baskets, lest they soil the fruit, but only on the sides. Our mishnah discusses what became of those young birds.
The text of the Mishnah:
"HaGozalos she'al gabei hasalim hayu olos" - the birds that were hung on the baskets, more precisely on their sides, were offered as an olah, a burnt offering.
"U'mah shebiyadam nosnim laKohanim" - the Rambam explains: the birds that were in the hands of those bringing the bikkurim were given to the kohanim as a gift.
"U'mah shebiyadam" - a second interpretation:
Some explain that the phrase "u'mah shebiyadam" does not refer to the birds at all, but to the baskets and the fruit that were in their hands. According to this interpretation, the birds were offered as burnt offerings, while the basket and the fruit inside it were given to the kohanim as bikkurim.
In summary: In this mishnah we learned about the birds that were hung on the sides of the bikkurim baskets as part of the adornment of the bikkurim - the birds on the baskets were offered as burnt offerings, and regarding the question of "mah shebiyadam" the commentators differ: according to the Rambam it refers to birds that were given to the kohanim as a gift, and according to another view it refers to the baskets and the fruit that were given to the kohanim as bikkurim.