I also have been searching for these rails for several days now (which is how I found your post) as I purchased this crib a few months ago and was told they didn't have the rails at the time (which could have just been lack of knowledge on their part). I found two sites thanks to the other responses, including Babies R Us that say they take standard rails.
Durable, versatile and beautiful, the Graco Lauren 4-in-1 Convertible Crib is certified to be safe. Simple yet elegant in style, this sturdy crib features stationary side rails for a safe sleeping environment for baby with a mattress platform that adjusts to three different heights depending on the age of your baby. This crib transitions easily to a toddler bed (no guard rail needed for conversion), daybed and full-size headboard. (bed frame not included)
However, it's supposed to convert to a toddler bed. How is the different from their definition of a daybed?
happilyhis:I have this crib and I also don't understand how it could convert to a toddler bed...maybe using the sides/ends as headboard and footboard instead of the front and back? We are converting to a full size bed using regular bed rails.
Just remove the front part of the crib.