I live in West Haven, but used to live in Monroe. We often went to Silverman's Farm, it really is nice but can get WAY crowded. Another option is Agway in Monroe, just as easy to get to. They have pumpkins but no patch, but do have a haymaze and animals, and a hay ride on weekends that takes you around the farm, the kids liked it. That is just off route 25 in Monroe on... geez what's that road now? You take the connector and go strait at the end onto rt. 25, head a couple miles up, take a right just past Duchess restaurant on your right, and go up about a half mile, you can't miss it on the left.
Another great one is Jones Tree Farm, on route 110 in Shelton, they do have a pumpkin patch, and a hay ride, don't know about a maze though, I don't think so. They also have a pay one price for all the pumpkins you can carry from point A to point B, I usually enjoy doing this myself hehe.... But, this place, like Silverman's, can get way crowded. Agway is your best bet to avoid a crowd, and it's well suited for a 2 1/2 year old to enjoy herself! And they have a ton of animals you can see, some in cages *mostly various chickens* and farm animals at the barn there, pigs, goats, small cows, etc. AND UNLIKE Silverman's, you don't have to PAY to see the animals! Back when I was a kid you could see the animals at Silverman's for free, but now they actually charge you, ridiculous! Agway you can enjoy all the animals for nothing, and the hay maze, which is smaller and for kids, that's free too, even the hay ride is free. Definitely the best bet.