I bought 6 chicks from Orscheln Farm and Home on the last Monday in May. 3 are Barred Rock, 2 are Rhode Island Red, 1 is "Rainbow Assorted" She is yellow in the front-quarters and white in the hind-quarters. I have no idea what breed she is. (she is the one in the center of image)
Welcome to BYC. She looks to be a mix. Most chicks labeled as "rainbow assorted" are bred mainly for egg production but not aesthetically pleasing to look at.
If it has a single comb(the regular type like on rhode island red or barred rock) probably one of those red sex links. If it has a pea comb plus a beard, easter egger.