A list of where each cactus flower can be found is here.
Blue Cactus Flower: 20 car coins each. There are 5 of these in Downtown Radiator Springs near thfe entrance to Fillmore's Fields, about 7 - 10 can be found in Willy's Butte, 3 are North and theres also another 3 near the entrance to Fillmore's Fields from Willy's Butte. These flowers seem to be the most common besides Corn and Golden Cactus Flowers.
Pink Cactus Flower: Willy's Butte only, when you first get here from Downtown Radiator Springs, take a left down a a dirt path, this is wear a majority of them are found, they are as many coins as Blue Cactus are and are always found in groups of 2, 3, or more. They are the most common flower in Willy's Butte.
Golden Cactus Flower: 10 car coins each, 5 - 6 can be found in Downtown Radiator Springs and 4 in Willy's Butte, the ones in Downtown grow back rapidly and a certain one that grew faster than others was called 'The money tree' one in Willy's Butte can be found on the first left dirt path coming from Downtown, another one is found near Fillmore's Fields entrance while 2 others can be found North.
Corn: 10 car coins each. Only found in Fillmore's Fields and is the only plant that can be found there as well. they are found in very large groups and there are about 7 - 20 there the large cornfield is protected by Frank.
Orange Cactus Flower: 50 coins each, there are about 5 - 7 found in Willy's Butte and can only be found in Willy's Butte, there is one in the open field North of the mud puddles, there is also 2 Southwest of there.
Totally Sweet Cactus Fruit: 70 coins each, most expensive yet rarist flower in the game, there are 4 found and in Willy's Butte only, one is near the Northwest Under Construction sign, another one is found near there and one is near the entrance of Willy's Butte Rally the final one is near the entrance, (from Downtown Radiator Springs) it is found near the mud puddles.
- Redhood Valley is the only place in Carburetor County with no flowers.
- Pink Cactus Flowers, Orange Cactus Flowers, and Totally Sweet Cactus fruits all can only be found in Willy's Butte.
- Willy's Butte has the most flowers and has every flower except for corn, Willy's Butte most likely has 20 - 30 flowers.
- The 5 Blue flowers near the entrance to Fillmore's Fields in Downtown RS were added on the last week of Mack's Holiday Bash, strangely, Neither Downtown RS or Fillmore's Fields have blue flowers, it's unknown how they have grown, possibly because the soil looks different.