You can post photos of your loved one's family members, but in some prisons, prisoners are not allowed to take photographs of themselves, which includes family snapshots. You can check with the family services team.

Photographs of an explicit or pornographic nature are not permitted. 

Certain prisoners may not be permitted to have photographs of children due to their offence/restrictions. 

Greeting cards are usually acceptable to send, although if posted by a loved one, the prison will photocopy the card and give it to the prisoner (for drug prevention reasons). Most prisons accept cards ordered via online companies, but you can check this with the family services team to avoid disappointment.