Muhammad Miracles!

Muhammad performed many phisical miracles witnessed. The miracles that Muhammad did were performed in front of the people eyes so them they believe him when he said, ‘I am God’s Messenger.’ 
This were the miracles that Muhammad desired at the time he choose:

“And they say, ‘We will not believe you until you break open for us from the ground a spring, or [until] you have a garden of date-palms  and grapes and make rivers gush forth within them in force [and abundance] or you make the heaven fall upon us in fragments as you have claimed or you bring God and the angels before [us] or you have a house of ornament [gold] or you ascend into the sky.  And [even then], we will not believe in your ascension until you bring down to us a book we may read.’  ‘Say, Exalted is my Lord!  Was I ever but a human messenger?’’’ (Quran 17:90-93)

The answer was:

“And nothing has prevented Us from sending [this message, like the earlier ones,] with miraculous signs [in its wake], save [Our knowledge] that the people of olden times [only too often] gave the lie to them: thus, We provided for [the tribe of] Thamud the she-camel as a visible sign, but they wronged her.  And never did We send those signs for any other purpose than to convey a warning.” (Quran 17:59)

When demanded ostensibly, God in His wisdom knew they would not believe, so He refused to show them miracles:

“Now they swear by God with their most solemn oaths that if a miracle were shown to them, they would indeed believe in this [divine writ].  Say: ‘Miracles are in the power of God alone.’  ‘And for all you know, even if one should be shown to them, they would not believe so long as We keep their hearts and their eyes turned [away from the truth], even as they did not believe in it in the first instance: and [so] We shall leave them in their overweening arrogance, blindly stumbling to and fro.’” (Quran 6:109-110)

In Medina Muhammad used to say sermons learning on a tree stump. But when the number of worshippers increased someone suggested Muhammad to built a pulpit so Muhammad listened to him and he built the pulpit. When Muhammad abandoned the tree trunk something happened. Abdullah ibn Umar, one of the companions, gave an eye-witness testimony of what happened. He say to Muhammad that the tree trunk was crying and that he listened when that happened. The event was confirmed through eye-witness.

Muhammad exorcised the devil out from a boy by only saying ‘Come out!  I am Muhammad, the Messenger of God!’ and the demon come out of the boy.

In more than one ocassion people were indire need of water and Muhammad saved them. Only by putting his hands in the vessel and water began to flow thorugh Muhammads fingers. 

http://www.islamreligion.com/articles/152/