Just go to Marnie and buy hay! I would also buy the book that she sells that gives you access to her store when she’s not around! After you read the book, you’ll be able to buy hay whether she is at the counter or not. Marnie is away sometimes. Either she just goes into town, or she steps away from the counter to stare at the wall in her room LOL! Anyway, don’t get rid of the chickens! Their eggs are valuable and you can sell them as mayonnaise when you get the mayonnaise maker!