By nature of the differences between English and Japanese (in this case the comparitively clumsy way English shows possession) - this is really difficult to translate:

Kaeri's Kangaroo, the one she is able to buy, that kangaroo's frog changed its mind.

Naturally enough, the translation loses everything and is hardly worth mentioning. This is also a play on synonyms in Japanese where the word pronounced kaeru 「かえる」 can sound like several words (in this case to buy (potential form), frog, and to change). Also the word kangaroo sounds a lot like kangaeru 「かんがえる」 - which is the verb for to think. Fortunately, because of the system of using Kanji characters, all of these are written totally differently and there's really no confusion when reading it.

娘の昔のママのマシュマロにマロンを入れて丸める

Put your daughter's old mother's marshmallow in the melon and roll it up

This one is almost a tongue twister in English as well. Once again here, we have a lot of possessive going on (daughter's mother's marshmellow) which, in Japanese, doesn't seem to be as awkward as it is in English.

The symphony that Kyoko wrote today, was composed in a textbook at Tokyo public park canyon

This is a play on many similar words sounding like 'kyo' 「きょ」 - such as the name Kyoko. The fact that the word for 'symphony' is practically a tongue twister in itself, really helps - kou-kyou-kyoku ｢こうきょうきょく」