I'm trying to find out where artists get those cheesy stereotypical scratch samples a la 24K Magic (Bruno Mars), My Name Is (Eminem), 69 Boyz songs, etc. Maybe they're from some ROMpler keyboard?
The opening scratch to "My Name Is" is a baby scratch of a kick drum sound. "24K magic" also has a baby scratch of a kick drum. So I'd guess that's what you mean.
It may be a sample but it's probably just a normally performed scratch (probably with a turntable on Eminem and probably some kind of controller on Bruno Mars). The reason it gets used everywhere and thus sounds cliche is not that it's a sample but just that the "baby scratch" is the easiest one to perform. It's the first scratch every DJ learns because it's literally just moving the record back and forth while the fader is completely open.
And using a kick sound—whether it's a baby scratch or something more advanced—like this as a fill or lead-in to a new part of the song has become sort of idiomatic over time.
I know that samples used in Bruno Mars songs exist in this package. Not all, but a lot of them.