It's the end of the topic, so it's time to go a bit crazy.

Draw a field of flowers, and give each flower a different color, size, shape, position, and so forth. Use some of the simple custom blocks you've already written, and write new custom blocks that make use of those simpler blocks to do complicated things.

Use repeat block to draw lots of flowers, flowers with lots of petals, and so forth.

Use pick random block as much as you can to make the flowers interesting and different.

Here is a custom block (from someone who went crazy) to give you some ideas:

crazy complicated draw flower block with tons of inputs

And, you could use this starter project, which contains a few fun backgrounds. To use them, click on the Stage sprite at the lower right of the Snap! window, select the Costumes tab at the top of the scripting area, and select the background that you want for your program.