Players need to place Warning Signs at a Crop Circle for a Foreshadowing Quest. Originally, there was only a single crop circle with additional ones now popping up.
Where to Place Warning Signs at a Crop Circle in Fortnite’s Foreshadowing Quest
It seems the Alien Invasion leaks were correct, as more and more of these Foreshadowing Quests are pointing to Aliens touching down on the map, likely following the start of the next season soon.
Another aptly named Foreshadowing Quest, this one taking the player to Colossal Crops, naturally. While this location may be highly contested due to everyone completing their challenge, it's tough to miss the crop circle when dropping in on the location at the start of the game.
All you must do to get credit for completing the quest is walk to the center of the crop circle and interact with it. Completing this quest gives you a nice chunk of 2400 XP!