'pickup' changes how you pick up items when you step on them.
to pickup an item manually, use the ',' key.

Mode 0: Don't pick up items.
Mode 1: Pick up one item 
Mode 2: Pickup up one item and stop
Mode 3: Stop before picking up items
Mode 4: Pick up all items
Mode 5: Pick up all items and stop
Mode 6: Pick up all magical items
Mode 7: Pick up all coins and gems

Modes above 7: Pickup items with
a value density greater than the pickup mode.

Value density is value in gold/weight in kilograms.

The value in gold is what the item is worth if you
sold it in the shop.

Goldcoins have a value density of 66,

Density 10 will pickup silver, gold,
rings, wands, books, and scrolls.
Artifacts are also picked up.