These are in a friend's garden and my friend wants to know what these are, so that he may need to plant them in the right places because they are volunteer seedlings.

Top plant looks like a phyllanthus, not a keeper... But hopefully it's something else.

Bottom might be Althea.

This is only a guess.
For the second of your two photos - Are there any Podranea ricasoliana vines in the area?
Edited to add:

Dinu, here is a photo that you added to the database.

Looks like Moringa oleifera to me. Take a peek?
http://moringafacts.net/#
http://tierra-moringa.com/

Dinu,

the first one looks like Robinia pseudoacacia to me.

Black Locust (Robinia pseudoacacia)

ursula

Dinu,
Is your friend's garden in Mysore, India? or some other location? Knowing the location of the garden might be helpful.

Oh sorry, I slept over this one.... long time since the last post. In the meanwhile I personally got too busy with preparations for DD's wedding [Jan 20]. Still busy, but taking a few minutes to take a peek. In fact, have never stopped visiting. Now my friend's garden too would have taken a different shape. It is in Mexico.

The top looks like my honey locust tree volunteers. Many of the locust and acacia trees have the same appearance with different flowers when matures.

The first one does look like a Black Locust.