Whatever you do, don't eat the delicious cards.

If an effect refers to a Food, it means any Food artifact, not just a Food artifact token. For example, you can sacrifice Tough Cookie (an Artifact Creature — Food Golem) to activate Maraleaf Rider's ability (an ability with "Sacrifice a Food" in its cost).

Food is an artifact type. Even though it appears on some creatures, it's never a creature type.

You can't sacrifice a Food to pay multiple costs. For example, you can't sacrifice a Food token to activate its own ability and also to activate Maraleaf Rider's ability.

You repeat the process as part of the resolution of Insatiable Frugivore's first ability. If the Food token you created or the cards you exiled from your graveyard caused any abilities to trigger, those abilities won't go on the stack until after Insatiable Frugivore's first ability has finished resolving.

Players can't take other actions during the resolution of Insatiable Frugivore's first ability. Notably, they can't try to remove cards from your graveyard between repetitions of this process.

The process in Insatiable Frugivore's first ability is repeated until you decline to exile three cards from your graveyard. You can't try to exile three cards from your graveyard if you don't have at least three cards in your graveyard.

You can choose 0 for the value of X in the cost of Insatiable Frugivore's last ability. If you do, creatures you control will just gain menace until end of turn. (The mere idea of someone eating berries like that is scary enough, apparently.)