I am already pulling the parameters from the stored proc sent in like this:
foreach (SqlParameter param in cmd.Parameters)
{
if (
If you are looking at developing tools for management of SQL Server objects then a better option may be SMO. It looks like you can get to the default value of a stored procedure parameter using the StoredProcedureParameter Class.
http://msdn.microsoft.com/en-us/library/microsoft.sqlserver.management.smo.parameter.defaultvalue(v=SQL.100).aspx