cream spray rose, Gypsophilia (babies breath), dusty miller (grey leaves), spirea (green leafy foliage with tiny white flowers), seeded Eucalyptus (brown and green seed like stems), and pale pink stock.
example of white spray roses in a boutonniere. could include one or two blooms. these also include a bit of greenery, but wouldn't have to. could keep them simple with just the bloom, or add a stem of something to trim such as sweet pea, astilbe, etc.