Did Shakayamuni Buddha talk about the Trikaya? If so where? I am looking for suttas attributed to Shakyamuni in the times of Theravada.
It wasn't explicit in the Theravada but the foundation was already there. The concept got fully developed by the time of the Mahayana. Further info. is available from the wiki page here
No but the concept of dharmakaya in Theravada is known as dhammakaya.
The ideas of sambhogakaya and nirmanakaya (rupakaya) on the other hand were not developed fully until Mahayana entered the picture.
According to the same Wikipedia entry, it is possible the idea of some form of rupa-kaya was taking shape though as this passage (section 9) from the Aggañña Sutta may indicate:
"I am a true son of Blessed Lord, born of his mouth, born of Dhamma, created by Dhamma, an heir of Dhamma." Why is that? Because, Vasettha, this designates the Tathagata: "The Body of Dhamma", that is, "The Body of Brahma", or "Become Dhamma", that is, "Become Brahma"."
This may be a misinterpretation of sutta taken out of context because it does not seem to be repeated through other Theravadin literatures.