Oh, yes! Dogs can have seasonal allergies!!! Mine has seasonal (weeds and grasses) allergies, food allergies, and is even allergic to humans. His allergies are considered pre-existing conditions now, so pet insurance is not an option for us.
Your vet will probably start your dog on Benadryl, but we've also had prescriptions for hydroxyzine and Zyrtec for our dog (only use these with your vet's dosing instructions).
A simple thing you can do is to wipe off your dog with a damp cloth to get any pollen off of her paws and belly. It will keep her from tracking outdoor allergens inside, just as you would prevent by taking off your shoes at the door.