The CactusForage mod adds 28 new species of cacti to various biomes that add color and food to the world. Wait (patiently) for the cacti to grow, flower, and fruit before harvesting a fruit (might want to use shears if it's a spiny one!). Craft seeds from the fruit or simply shear off a pad (if it's a prickly pear) to plant your own seedlings and get started on your own garden.
The cactus fruit can be combined in various ways along with wheat to make 9 new baked goods items. It can also be eaten raw, but may not be the most filling meal if done so.
Biomes the cacti spawn in include (but are not limited to) the desert, badlands, savanna, windswept hills, plains, meadow, and much more! Many are very rare and hard to spot, but you can try and collect them all.
Planned updates may include more non-cacti specific foraging options such as harvesting and leaching acorns from oak trees to make acorn baked goods, and perhaps more berries or cold-biome specific forageables.
I wonder if they grow in other dimensions?
Pricklypears can be pretty common and luckily have delicious red fruits! You can harvest them with your raw hands but those glochids are no joke, using shears might be in order... probably don't want to touch it either.
...Some cacti have red flowers instead! The fruit color will be different, but sometimes it's green, so the fruit will blend in a bit.
Some smaller cacti have similarly smaller berry-like fruits. They aren't more than a light snack on their own, but I wonder what they might go well with...
Sadly, not all cacti fruit were meant to be eaten. If the fruit is tan or brown, it's likely a dry fruit and is little more than a dry carrier for seeds. Wait for the fruit to dehisce and the seeds will pop out on their own.
Craft seeds from the fruits you harvest to get cactus seeds you can use to make your own garden. Just be sure to have patience, a lot of cacti are slow growers...
Pricklypears don't grow well from seeds, so the seeds from these plants are mostly useless. Shear off a pad instead and stick it directly into the ground, it'll grow on its own!
Some cacti are quite small and quite rare, making it hard to find many species. Most biomes where cacti spawn have a biome exclusive rare cactus. I wonder what would happen if you collected them all...
Use your harvested fruit to make some delicious treats. I bet some cactus berries would go great in a muffin mix!