<asp:DynamicControl Test="Hello field" id="MyID" runat="server" DataField="MyField" Mode="Edit" />

public string Test { get; set; }

<asp:DynamicControl Test="<%# this.MyObject %>" id="MyID" runat="server" DataField="MyField" Mode="Edit" />

protected MyClass MyObject
    {
        get
        {
            if (this.o == null)
            {
                this.o = new MyClass();
            }

            return this.o;
        }
    }

public MyClass Test { get; set; }

<asp:DynamicControl Test="<%# Eval("MyProperty") %>" id="MyID" runat="server" DataField="MyField" Mode="Edit" />