Make the herb butter: Pulse the butter and herbs in a food processor until well combined. Form into a log on a sheet of parchment paper, wrap and refrigerate until firm, at least 30 minutes.
Prepare the seafood boil: Combine the salt, coriander seeds, fennel seeds, peppercorns, bay leaves, red pepper flakes, thyme, onions, celery, tomatoes, lemons and garlic in a large deep pot; add 6 quarts water. Cover and bring to a boil; uncover and cook 10 minutes. Add the wine and potatoes and return to a simmer; cook until the potatoes are just tender, about 20 minutes. Add the corn and boil until tender, about 8 more minutes.
Meanwhile, cut each lobster in half with a chef's knife, starting at the cross mark on the back of the head (the lobster may continue to move for a minute). Remove the green tomalley and roe, if desired.
Remove the corn and potatoes from the pot using a slotted spoon and transfer to a platter (it's OK if you remove some of the broth ingredients, too); cover with foil to keep warm. Add the lobsters to the pot and cook until the shells turn pink, 3 to 4 minutes. Add the mussels, pushing them down into the broth. Cover and cook, stirring once or twice, until the mussels open, about 5 minutes. Transfer the lobsters and mussels to a platter. (Discard any mussels that do not open.)
Strain the broth through a fine-mesh sieve into a small saucepan. Slice the herb butter. Pour the broth into bowls; add the vegetables, seafood and some of the herb butter.