Hierva buena ( or yerba buena) means 'good herb' 'beneficial herb'. 'Paico' is sometimes used for Wormwood so I'd check out comparisons of those plants. If so, I'd not use it in cooking. 'Paico' is also cited as the common name of a Central American native, Chenopodium ambrosioides. I'll attach a picture of that for you.

Here is a link that might be useful: Click here

It could be Epazote, Chemopodium ambrosioides. Or even spearmint, or something tasting like it, which is my guess.

This Wikipedia article lists a number of herbs going by the name 'Yerba buena'. Literal translation, as Rhizo1 says, is simply 'good herb'.

Or check here: http://www.ibiblio.org/pfaf/cgi-bin/find_lat?LAT=&COM=yerba+buena&FAM=&RATING=1

Here is a link that might be useful: yerba buena

Thanks! I think it might be Epazote also known as Chemopodium ambrosioides. The smell reminds me of Cuban Oregano and this article mentions Peruvians use the name Paico, which is where my friend is from.

http://www.rain-tree.com/epazote.htm

I will take a picture later when it stops raining and it gets a little lighter out. I don't know why I didn't include a picture with this post in the first place.
It doesn't sound like anything I would want to add to soup casually unless I want to deworm my family. Interesting herb though.

Here is a link that might be useful: Raintree Nutrition database for Epazote

Epazote is often used in bean dishes. It tastes (to me) like a cross between mint and mineral turpentine!

Below is a link to a site with lots of recipes using epazote. There are many more sites you could look at if you do a Google search.

Here is a link that might be useful: epazote recipes

Im from Central America, Hierba Buena is the common mint in my country.

Hierba Buena is, as venusruiz said, mint. Paico is an herb from Peru; it grew wild in my parents farm. I remember it only being used in some type of soup made with crawfish or crayfish, cream, & cheese among other ingredients--it gave this dish a very distinct and excellent flavor. I also remember that some people would recommend an warm infusion of Paico for an upset stomach. As to the flavor or smell, I have never found anything in the US that closely resembles Paico's; nevertheless, it has a very pleasant taste and smell--but then I grew up perceiving it so.

It is Epazote / Chemopodium ambrosioides for certain. I saw a labeled plant at the WellSweep Herb Garden and there was no mistaking it. Thank you all. I knew you could figure it out.
Daisyduckworth, I don't exactly agree with your assessment of mint and mineral turpentine. To me, it is more like mint and mothballs but thanks for the recipes. Actually, they look very interesting at first glance. I'm not use to cooking those types of seafoods. It could be an adventure.
Still, I am uncomfortable about whether or not to try this. The article says that the seeds are too toxic but the leaves are not but I'm not too trusting of that information.

Planta arom�tica silvestre, muy conocida y apreciada. Crece como maleza en el campo, huertos y jardines. Propiedades: Los cogollos o ramas en infusi�n -15 a 20 gramos por litro de agua- se torna por tazas o a pasto, para curar las indigestiones, c�licos, calambres, afecciones o desarreglos y dolores de est�mago., dispepsia y v�as digestivas. Evita y cura los empachos, y elimina las lombrices de los ni�os de toda edad; adem�s cura las nerviosidades, desasosiego, malestar y llanto de las guaguas.

Es estimulante, digestivo y excita la transpiraci�n. Es muy �til y eficaz contra la disenter�a, catarros de est�mago, histeria, pleures�a, para expulsar las lombrices intestinales y para regularizar menstruaci�n. Las ra�ces se usan para curar el empacho de los ni�os.

Para curar la par�lisis de la lengua, se recomienda hacer hervir durante 10 minutos -30 gramos de ra�z de Paico en un litro de agua- se cuela bien y se hacen g�rgaras cada hora. El principio activo del Paico es el Ascaridol.

Here is a link that might be useful: hierba Paico