I don't know what to do about this one but next time I'd mark my blocks. Put them in a bag or a box and write the name of the quilt that they're intended for on the outside.
Could you maybe use a fabric just a shade darker for the next three rows, then another a little darker for the next three and so on until you get to the end so that it's a shade change effect? It might turn out really cool. Or go a little darker each row until your reach the last three and have them all the same dark shade.