Cutworms - can’t remember what the exact name is at the moment, but there is a kind for which collars don’t work. IIRC can cut the stalk up about a foot from the ground.
Didn’t ever find a good solution to the problem other than to check them out at midnight, and pick the murders off the stalks to dispose of them.
Hubby was at our local Walmart the other day, and while most of the tomato plants were in the $3 to $4 range, they actually had a big plant for around $13 dollars. $13 dollars buys a lot of seeds.
No way I'd pay that much for a veg plant. I walked past their $3 ones hoping to scan the $1.50 ones at the grocery store. Of course, the grocery store didn't have anything. Oh, well, have more seeds than any 10 people.