Translation:Kateřina and František often pick mushrooms.
Isn't "sbírají" more like gathering or collecting than "picking"? Is it just "picking" because that's usual in English?
Yes and yes. Sbírat has little wider meaning. We "sbíráme" mushrooms, laundry from cloth lines, stamps, collectibles of any kind, bluberries, apples (you can also "trhat jablka" = rip apples literally?), anything we dropped on the floor, etc. And English picks most of them. Specially when it comes to fruits and veggies.