Make an item's value equal zero in drop down list

I added an item to a drop down list located in a DataGrid in the ItemDataBound event.
The drop down list is first populated from the database like this:

Public Function FillDropdown() As System.Data.SqlClient.SqlDataReader
      Return Catalog.GetGifts
End Function

<asp:DropDownList ID="ddlGifts" DataSource='<%# FillDropDown %>' DataValueField="GiftID" DataTextField="Event" Runat=server></asp:DropDownList>

I need to set its VALUE to zero so I can check for this value later.  
This works but it doesn't set it's VALUE to zero:

Private Sub productsGrid_ItemDataBound
.....................
Dim ddl As DropDownList
ddl = e.Item.Cells(1).FindControl("ddlGifts")
ddl.Items.Insert(0, "Select Gift Category")  << need to make the Value = 0


Right now, this (Gift) equals "Select Gift Category" not zero, which I need:

Dim Gift As String = CType(e.Item.Cells(1).FindControl("ddlGifts"), DropDownList).SelectedValue