There's any SAP table that shows all the landscapes (and respective clients) in a server?
I need a list with the Development, Quality and Production landscapes, and they respective clients to work with in a FM.
List of SAP clients can be obtained from T000 table. Don't know what do you mean under landscapes as SAP system is a part of only one landscape usually. It can be included in several landscapes but this configuration is rather unusual. More on this here.
I suppose you mean systems that form Transport Domain, if so they are listed in TMSCSYS table.