Well, the first Pokémon card was actually given to me, a Spearow common from Crystal Guardians that a relative had no want for. I gladly accepted the card along with a few of his energy doubles he didn't need.
My first product that I bought was the Steel Sentinel theme deck from HS Unleashed, back when they gave you loads more doubles, more energy, and only 3 rares. Still, that Holo Steelix and Regular Rares Roserade and Primeape will always be special.
As for my first pack, that actually came with the next theme deck I bought, the HS Undaunted Daybreak Deck. I remember being really thrilled, and getting a Muk, Raticate, Foil Gloom, Misdreavus, Togetic (I think), and perhaps an Eevee (can't remember the rest off the top of my head). That Weavile Rare looks just as cool today as it did that day (and is also still quite useful)!
Ultra Rare wise, Umbreon Prime. Looks better than any Full Art card, even without texture. I think I flipped at the time, and pulled a holo too!