Dear Dr Ashok Ghosh Ji,

Please have a look at this useful link.

https://sites.google.com/site/efloraofindia/species/a---l/f/fabaceae/crotalaria

Good luck

1st one is Alysicarpus sp., and 2nd one is Polygala crotalarioides .

First one could be Crotalaria prostrata

Second one is Polygala chinensis of family Polygalaceae. 

The first picture I agree with Arvind Singh  and is also close to Crotalaria evolvuloides

Https://sites.google.com/site/efloraofindia/species/a---l/f/fabaceae/crotalaria/crotalaria-evolvuloides

The second picture I think is Crotalaria retusa L.(https://sites.google.com/site/biodiversidadecatarinense/plantae/magnoliophyta/fabaceae/crotalaria-retusa)

Thank you everybody for your comment, suggestion, important link. I'll check every possibility.

Thank you.

ASOK GhOSH, BU