The description of the druid's Wild Shape feature makes it clear that, whilst transformed:
You can't cast spells [...]
With the caveat that:
Transforming doesn't break your concentration on a spell you've already cast, however, or prevent you from taking actions that are part of a spell, such as call lightning, that you've already cast.
The description of the Ready action says, in part:
When you ready a spell, you cast it as normal but hold its energy [...] and holding onto the spell's magic requires concentration.
Could a druid therefore ready a spell, Wild Shape into a beast, and then release the energy of the readied spell?
To give a more concrete example, could I have my druid:
- Ready the beast bond spell
- Wild Shape into a bear, to better win the friendship of a bear and thus make her an eligible target for the spell
- Release the energy of the readied spell, with the newly befriended bear as the target?