The third book of the Aṅguttara Nikāya, the Collection of the Numbered Discourses of the Buddha, collects 352 suttas or discourses whose themes are centered on groups of three topics. For example, suttas are collected, not exhaustively, that speak of the three emotional reactions: pleasant, unpleasant and indifferent. There are other different suttas included in other collections  that are not in this one.
The Book of Threes breaks with the purely mnemonic mechanics of the “matikas” series of the first two books. This is a book made to be read. Even so, both its subject matter and its content are far from interesting since they neither recount the life of the Buddha nor do they include unique doctrinal principles.
Perhaps the most interesting sutta is AN 3.65: With the kālamas of Kesamutta, which deals with the adoption of a belief based on results and not on fallacies. It is a long and interesting sutta.
On the opposite side and marked with a double asterisk (**), we find a couple of extemporaneous suttas, out of context, with a particular structure and spurious content. These are suttas AN 3.80: Minor and AN 3.107: Laments.
“Minor” is a discourse similar both structurally and in content to the decadent suttas that Gogerly found upon his arrival in Sri Lanka in the 19th century, characterized by describing the Buddha as a mythological and fantastic being endowed with magical powers, much to the taste of eastern excess. So here we can see the Buddha giving voices that are heard in all the galaxies and, at the end of the sutta, the imagination overflows when the Buddha becomes a prophet, predicting that: "Ānanda will be extinguished in the present life", which turned out fake. Every false sutta brings a bastard intention, and in this case it is to underline the orthodoxy and reliability of one of those responsible for the First Council who, far from being a Worthy, did not even achieve anything since he was more busy dealing in tunics than in the practice.
The other apocryphal sutta is AN 3.107: Laments, a strangely structured sutta that comes to be a scolding against people who listen to music, or laugh. The author did not dare to assign the authorship of the rebuke to the Buddha and left it to a simple "it is considered".