The Paypal Standard payment for osCommerce v2.3 doesn't provide the detailed item list in the Paypal invoice, but simply your store name and the subtotal.
This is a simple fix for it. By replacing some code, the paypal invoice can display the item name, quantity, and unit price item by item, subtotal and more.
If you want to improve it, simply refer to the Paypal doc:
Chapter 5 and Table A.6.
Hope it can help!