Solomon is a chem dealer who runs his shop, Chem-I-Care, from within the Diamond City Market. Practically everyone in the stadium buys chems from him, from security guards needing a hit of Psycho, or an engineer needing a box of Mentats, and radiation medicine is universally sought after.[1]
Accordingly, he has employed at least a few people to find mutated fern for him which are fantastic for synthesizing radiation medicine.[2] While he doesn't explicitly mention sending anyone else, he has sent at least one other person to the Forest Grove Marsh, but they did not return with ferns in hand.[3]
↑The Sole Survivor: "Did you say something about drugs?" Solomon: "That's right. All the chems you need to fill out your lifestyle. Balance you out. Everyone here buys from me. Sometimes security needs a little Psycho, or an engineer needs some Mentats. And heck, Rad-X is plain universal." (Solomon's dialogue)
↑The Sole Survivor: "Looking for a job, if you got one." Solomon: "Yeah, I got something. Looking for a Mutated Fern if you find any.I hear some grows out near Forest Grove Marsh. Natural radiation sucker. Be great for cooking RadX or RadAway." The Sole Survivor: "What did you need again?" Solomon: "Mutated Fern. Hear it's dynamite for making radiation meds. You interested?" (Solomon's dialogue)
↑The Sole Survivor: "Can I put this on my charge card?" Solomon: "Hey, I know money's kind of an imaginary thing anyway, but that card is like... way more imaginary than I'm comfortable with." (Solomon's dialogue)
