What would be a good wedding color flower palette for this theme?

The colors in the wedding are grey and yellow. But, it is not a bright flashy yellow, but a soft er type of yellow. A lot of the yellow flowers we see are super bright yellow, and we don't want that. Any suggestions? The bride is looking toward yellow roses, but again, doesn't want a bright yellow to blind people. It is an outdoor rustic wedding in the summer in South Dakota.