I wouldn't know where to collect those. Is it possible to buy manzanita at a store? Maybe a mexican shop? What do they call it?
I hope you get this all worked out soon!
I just pick it off bushes if you don't know where to get it then uva ursi will do they are in the same family and have similar attributes use one or the other which ever you can find.
when I lived in Portlan and Vancouver comfrey grew in the cracks of sidewalks it was so common and abundant. The primary weed being blackberries then somewhere in there is comfrey and saint john's wort.
So if you live in the north country but don't know your plants there should be an herb store or an herbalist to be found in the region -- what you want is some loose green bulk herbs.
I've seen comfrey around but not manzanita