Can you elaborate more to answer the questions some others Mamapedia members have raised?
Is this a licensed day care center? Is it a for-profit or a non-profit institution? In a for-profit program, there should not be volunteers getting in your way. In a non-profit, I can see that there might be some need for volunteers, not necessarily in the child care room, but in other areas. When I was in 2 different community centers (both as a volunteer and as an employee), there was a need for volunteers to run fundraisers to make up the difference between child care fees and actual expenses. Sometimes, those who have been there for a long time have a sense of ownership of the program. That's not always helpful and it can be off-putting to new people coming in. However, when I was a board member at the center, I can tell you that it was the responsibility of the volunteers to really reach out to make connections to new parents and even to returning parents. However, parents were not volunteers in the classrooms except for very special programs where extra help was needed (visiting firefighters, visiting vet with animals, holiday parties, etc.).
If you are foreign-born, you are, unfortunately, used to some people not being so welcoming or open. But be careful not to label everyone that way. I don't know how long you have been in this country, but if it's a relatively short amount of time, are you positive that you understand the body language and the common slang used by these women? Is it possible that you are misreading what they say/do?
And if you are new to day care in general, is it possible that you are wanting to stay in the room longer, when the center staff may feel it's better to say a quick goodbye to your child and then leave? Maybe you are feeling that they are rushing you out of the room and you see that as rudeness, when in fact it is very likely that this is viewed as a benefit to your child to not belabor the farewell rituals and to help the child transfer quickly to the caregivers? That is very common in day care centers, and while it may feel odd or dismissive to you, it isn't meant that way at all.
What's important is that you not let other people's behavior upset you so much. If people are jerks, you cannot let them hurt you so much. It says more about them than it does about you. You cannot make other people have manners. Your entire concern should be with the caregiver working with your child. If you feel that person is unprofessional, then speak privately to the center director. While there, you can ask what the recommended policy is for drop off and pick up, and ask if you are misreading anything on the part of the other parents/volunteers. If you don't feel welcome and are reading it correctly, then the director needs to know. If you are misreading it, the director may be able to help you understand what people's intent is, and what you should do to make things better.
My feeling from your brief post is that you are new to this situation and that you may need more information and experience with the day care center to fully evaluate the reception you are getting. I hope that, if you reach out for help and understanding, they will assist you in making the transition to day care mom.