I love these two plant combinations - the yellow on yellow and below that picture, the pink on pink.
First, we have Lilies and this other perennial (I don't know yet what it is. If you know, please comment. Eventually I will look it up):
Next, Phlox and Hibiscus with Hollyhocks (Alcea) in the background:
ADDED: the yellow perennial is yellow loosestrife, Lysimachia puntata.