Les feuilles mortes se ramassent à la pelle

Can be translated “Dead leaves are picked up by the shovel” that’s the meaning of se ramasser.

For the meaning of

C’est une chanson qui nous ressemble

I imagine it is subject to interpretation but IMO he says that their love story reminds him the lyrics of the song. Their love is represented by the leaves.

They were living together and loving eachother but time fly and their love fade away, and in the end, the only things remainings is the memories of this love that is swept away by the winds.

We could say much more of the lyrics but i’m no expert (and I don’t have much time now 🙂 )

Se ramasser à la pelle has a double meaning in these famous Jacques Prévert’s lyrics.

Literally, the first verse means “dead leaves are collected with a shovel” but figuratively, that also means that there is a very large number of dead leaves.

TLFi

− Loc. adv., fam. À la pelle. En grande quantité. On devait, disait-il, trouver là de l’or à la pelle (Zola, Germinal, 1885, p.1201). Les vendeurs d’orviétan, les discoureurs philosophiques, qui remuaient à la pelle des idées générales, avec le paradis social au bout (Rolland, J.-Chr., Foire, 1908, p.767).

Of course, when referring to abstract things like souvenirs or regrets, only the figurative meaning makes sense.