From the OP's code, modified for my machine for demo:
Add-PSSnapin SqlServerCmdletSnapin100 -ErrorAction SilentlyContinue
Add-PSSnapin SqlServerProviderSnapin100 -ErrorAction SilentlyContinue
Set-Location SQLSERVER:\SQL\MyComputer\MyInstanceName\Databases\MyDataseName\StoredProcedures
Get-ChildItem | Select Name
I only receive a list of user-defined procs.
There are no special teachers of virtue, because virtue is taught by the whole community.
--Plato