This is a unique alternative use for your mismatched forks. Great not just for pictures, but for holding cards or notes as well. Though it seems to require some hand strength, this DIY project is easy.
Turn the outer tines of the fork backwards. Make sure they are equally bent.
Then grab the inner ones, one at a time and pull it up and out. Bend the tips to make a little curl where your pictures can securely stand.
You might want to interchange the tines – inner tines bent backwards and outer ones forward – if you want to have a wider holder, and if you think it would be possible given the fork you have.
Source: Pots and Pins Blog