Can anyone help me to find some LinkedIn bounty campaign?
You really have to check the bounty threads one by one because even there is a list, it will become outdated in no time. Just look at the references above, some of the bounties are closed now.
If you really want to find some then make an effort and spend time looking on it.
Bounty hunters spend time lurking on bounty section to find their specific needs, you must do the same.