Hi A.!
I am a teacher and taught first grade for a number of years. If you haven't yet received a list of supplies needed from your daughter's teacher, then you'll probably get one on the first day of school. I would get some of the basics: a backpack, a good supply of pencils, a hand held pencil sharpener, chunky erasers (not the pencil top kind - they break too easily), a pair of child friendly scissors, a couple of glue sticks, crayons, markers, and a couple of the pocket folders.
Every classroom teacher runs things differently - some may ask you to contribute to a "classroom supply" so the teacher can pass things out to students as needed. Other teachers may ask that each child supply their own items. It really depends on the what the school is willing to supply, and how the teacher wants things done. If you don't want to buy all of the things above until you know more what her teacher will want, she'll be fine with a backpack, a few pencils and an eraser for her first day. If her school has a "meet the teacher" event - definitely attend if you can. Usually teachers will have their supply list handy at this event. If you can't attend, ask another parent to pick one up for you, or call the office and ask them to send one to you.
Sorry about the long, drawn out answer... can you tell I'm a teacher as well? :-)
Good luck - first grade is such a fun year!
-D.