While navigating on Tumblr I found a code that makes your Tumblr blog have "falling petals". If you wish to see a preview of it, I add the effect on My Example Blog. Take a look, if you like how it looks here's the tutorial:
1. Copy the from this page. CODE
2. Go to Settings, and open the Customize panel.
→ Settings → Customize → Edit Html
3. Paste the code before or after the code <head> CODE HERE </head>
→ Use Control + F to find the code → Paste the code
4. Click on Update Preview and the falling petals should appear.
→ Update Preview → Save → then close your Customize Panel
[code found at HERE]