All flowers and mushrooms should be placable by 4 on one block.

Now that we have a lot of decoration block that can be stacked by 4 on one block (sea pickles, candles, turtle eggs and the newer pink petals), all small plants, flowers and mushrooms should work the same. They could be naturally generated in a random number (something like 50% chance of 1 flower/block, 25% 2/block, 15% 3/block and 10% 4/block).
This would enhance the building possibilities and add a lot of variation in the natural world generation.