If my opponent has Ground Seal in play and I have a Crucible of Worlds, can I still play lands from my graveyard? I know Crucible of Worlds says nothing about targeting, so I assume it would not stop me from playing lands from my graveyard.
Your intuition is exactly correct - Crucible of Worlds doesn't target the land cards, so Ground Seal doesn't prevent it from working.
This is reinforced in the Gatherer rulings for Ground Seal:
Only spells and abilities that target cards in graveyards will be affected. Abilities that don’t target cards in graveyards (like the one Tormod’s Crypt has) can still affect those cards.