best way to represent table like data in collections
''' <summary>
''' creates a comma seperated string of all data
''' </summary>
''' <returns></returns>
''' <remarks></remarks>
Public Overrides Function ToString() As String
 ' some code to create a comma separated string of all data contained in the sorted    dictionary
End Function

''' <summary>
''' This class respresents a listItemCollection as provided in the constructor as table like data with headers and rows
''' </summary>
''' <remarks></remarks>
Public Class MetadataValuesFactory
    Private _fieldsNotToStore As List(Of String) = ConfigurationService.FieldValuesNotToStore
    Private _headers As MetaDataValue = New MetaDataValue()
    Private _rows As IList(Of MetaDataValue) = New List(Of MetaDataValue)

    ''' <summary>
    ''' returns a metaDAtvaleu object that contains all header values
    ''' </summary>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public Function GetHeaders() As MetaDataValue
        Dim result As MetaDataValue = New MetaDataValue()
        Dim displaynames = ConfigurationService.FieldValueDisplayNames
        For Each item In Me._headers
            Dim displayname = String.Empty
            If (displaynames.ContainsKey(item.Value)) Then
                result.Add(item.Key, displaynames.Item(item.Value))
            Else
                result.Add(item.Key, item.Value)
            End If
        Next
        Return result
    End Function

    ''' <summary>
    ''' Returns all rows that represent the values
    ''' </summary>
    ''' <returns></returns>
    ''' <remarks></remarks>
    Public Function GetRows() As IList(Of MetaDataValue)
        Return _rows
    End Function

    ''' <summary>
    ''' Creates a new metadatavaluesstore with the specified values
    ''' </summary>
    ''' <param name="listItems"></param>
    ''' <remarks></remarks>
    Sub New(listItems As ListItemCollection)
        'first store all values and make sure keys and values are matched
        Dim totalListItems = listItems.Count

        For index As Integer = 0 To totalListItems - 1
            Dim valuesToStore As MetaDataValue = New MetaDataValue()
            Dim item As SPClient.ListItem = listItems(index)
            Dim fieldValues = item.FieldValues

            For Each fieldValue In fieldValues
                If (Not _fieldsNotToStore.Contains(fieldValue.Key)) Then 'If it is not in this collection is must be stored
                    'Get index of field in _headers
                    Dim headerindex As Integer = _headers.Values.ToList().IndexOf(fieldValue.Key.ToString)
                    If (headerindex = -1) Then 'If fieldValue.Key is already in the array it doesn't need to be stored again (-1 = no index found)
                        'If Not exists then store header/key in _headers ánd set previous index to index of new headers value
                        headerindex = _headers.Count '' Add new header
                        _headers.Add(headerindex, fieldValue.Key.ToString)
                    End If
                    'add value to valuesstore
                    Dim valueToStore As String
                    If (fieldValue.Value Is Nothing) Then
                        valueToStore = String.Empty
                    Else
                        valueToStore = fieldValue.Value.ToString
                    End If
                    valuesToStore.Add(headerindex, valueToStore)
                End If
            Next
            _rows.Add(valuesToStore)
        Next
    End Sub

End Class

metaDataStreamWriter.WriteLine(metadataFactory.GetHeaders.ToString)
For Each storeValue In metadataFactory.GetRows
     metaDataStreamWriter.WriteLine(storeValue.ToString)
Next