Tea isn't in WWW seeds anymore, it's in teabushes. In your Map Options, make sure no bush but tea bush is checked, grab a throwaway alt and a boat, boat in one direction until you find teabushes, collect as many seeds as you like (once you start seeing teabushes you should find plenty, I'd go inland on the biome you saw the tea on, there should be more inland), hearth back.
Here's my experience with this:
To figure out where you are on that map, either zoom out, compare river/lake shapes, or better:
viewtopic.php?f=49&t=49027You might need to try a few different tiles, and I'd suggest "complicated" tiles, with lots of natural shapes/rivers/lakes and stuff, more unique it is the more likely it'll find you.