Autopickup

Ctrl-A           Toggle autopickup. Note that encounters with
                 invisible monsters always turns autopickup off.
                 You need to switch it on with Ctrl-A afterwards.

To add an item to the autopickup list, add an autopickup_exceptions line to your init.txt. For example:

 autopickup_exceptions = <stone, <artefact

The < character specifies an "inclusion" (matching objects should be picked up). Besides object names, you can also match against a number of prefixes, such as "artefact" (seen above), "emergency_item", and "unidentified".

The default configuration includes a number of such autopickup exceptions in the file autopickup_exceptions.txt. Note that exclusions override inclusions, so if your exception doesn't work make sure the object isn't matched by an exclusion in that file (useless_item is a likely culprit).

See the Picking up and Dropping section of the options guide for more details.