Creating Static parameter:
When you create a parameter, In the value field select the shift start field. Then click on "Actions" and select "Append All database Values".That will populate the list. When you insert that parameters in the report, you can select a value from the list.
Creating Dynamic Parameter:
You can create a dynamic parameter by selecting the dynamic option while creating a parameter. and select the shift start field. When you insert that parameters in the report, you can select a value from the list.
If you have any problems please let me know. You might be able to use command object. But I have not used that to create a parameter with dropdown list.