I dunno how many WWWs I've left on my herbalist table, but I only get pretty unremarkable seeds: lots of flax, pumpkin and hemp, with an occasional onion, and once even a peapod. Never once have I gotten a tobacco seed. Or a poppy seed.
Am I missing something? Does it matter what landscape the WWW was growing in when I picked it? Or what landscape my table is in (fir forest)? Or are the "drop rates" for tobacco etc just much, much lower?