Can cilantro be used for tea or tisane?
Cilantro is one of the herbs that doesn't retain much flavor when it's dried; it's unlikely to be particularly tasty when made into a tisane. On the other hand, the dried seeds of the plant -- called "coriander (seeds)"* --  have a pleasantly tangy and floral/citrusy taste.

They are occasionally used as a flavoring agent in beer, so it's perfectly reasonable to think of them as a candidate for tisane. The flavor of coriander is not dissimilar to chammomile, and might complement that. It would probably make an interesting mix with black tea, too -- in fact, it should be noted that coriander is sometimes an ingredient in Masala Chai, the sweet Indian tea-milk-spice drink.



*In the US, the leaves are referred to as "cilantro", whereas "coriander" most often means the seeds (although sometimes the leaves).