I have a question about my period???

ok the other day there was this brown stuff in my undies and it kinda looked liked skid marks but they wernt and i dont want to talk to my mom about it cause it will be embarasing for me and i dont want to explain why! but what is it and what should i be expecting from it? i am 11 1/2 i havnt had my first period yet i have brests and pubic hair... i need help pleaz any one out there help me...!!! :)