The Pebble
Scholars have said that seeing a bird descending from the sky, picking up a pebble, and flying away with it might indicate the death of a righteous man if it happens in a mosque. If the dreamer is ill, it could signify their demise. Picking up and collecting pebbles might indicate accumulating knowledge and Quranic understanding if from remembrance circles, or worldly benefits and money if from markets. Throwing pebbles has various connotations such as pilgrimage, praying against an enemy, or insults and slander.
Per Ibn Sirin's Muntakhab al-Kalam fi Tafsir al-Ahlam