class ActionController::Parameters

def each_value(&block)

the same way as Hash#each_value.
Convert all hashes in values into parameters, then yield each value in 
def each_value(&block)
  return to_enum(:each_value) unless block_given?
  @parameters.each_pair do |key, value|
    yield convert_hashes_to_parameters(key, value)
  end
  self
end