mutual thanks

Jane told to Honey ,"Thank you".
Honey also told to Jane, " Thank you".
Can I write the sentence like that,
"I heard the sounds of mutual thanks" ?

Uh .... no. You CAN say that they thanked each other.

Thank you so much.

If so, can i write like that " I heard they thanked each other" ?

Can I write " I heard their words of thanks each other"?

No, and no.

"I heard them thank each other."

and

"I heard their words of thanks to each other."

From a stylistic point of view, I wouldn't use #2 -- it sounds corny and flowery and sort of 19th century.

By the way, regarding the use of "sounds" when referring to speech, as in your example, "I heard the sounds of mutual thanks" -- usually you would only use that word when talking about speech whose content you can't quite understand -- when it's really just noise: the sounds of shouting in the street, I heard the sound of two people whispering, we heard the sounds of an argument coming from the next room, etc. Once you can make out the meaning and intent, you don't use the word "sound".

Also, regarding Honey and Jane:

Jane told to Honey ,"Thank you".
Honey also told to Jane, " Thank you".

A small correction: you can say "told", but not "told TO". If you use the word said, though, you will need to say "said TO". There are times when "told" is followed by "to", but this isn't one of them.