Olive ee, (ie) olive egger could be a cross of several different combinations, very common is Black Copper Marans over blue layer of any type, Such as BCM X CCL should give you approx. 50/50 roos/pullets and 50% brown layers and 50% olive egg layers, once you make the cross everything becomes a toss up on egg color, the proof is in the pudding so to speak, you have to breed and cull for egg color, if you don't succeed, change the sex of the breeds crossed, such as, Ameraucana roo over brown layer =olive egger, BCM over Ameraucana may produce Olive and brown eggers as my experience dictates, again, the proof comes in the offsprings eggs 6/7 months later