In French something en herbe means "budding"
I was on the bus this morning, and some school kids got in. A shy youngster of about 13 came and sat next to me. He was a bit uncomfortable, so I beamed a smile at him. After a short while, blinking furiously he said, 'You mowed the lawn this morning.' I was quite surprised, and with a smile he pointed at my shoes (I added some more grass to them when I got home, before taking the pic, for dramatic effect).
You're a budding Sherlock Holmes, I said, and he smiled. After a short while, I challenged him. Now, that was easy, or elementary if you like, tell me another thing about me. He hesitated, but came up with, 'You must be from Mauritius.' I was quite impressed. And how did you get that, young man? He straightened his throat first.
'Well sir, you look Indian, but I notice you have a slight French accent, so that was easy.'
Coming to think of it, I said, that was elementary too. I thought it best to leave the boy alone, but he had not done.
'Can I risk another deduction now?' Go ahead, I said happily.
'You must be a retired teacher.' I am, I nearly shouted, how did you work that out? He scratched his head.
'You're obviously not going to work, you've got a shopping bag, you're going shopping. So you must be retired.'
'OK, how did you guess I was a teacher?'
'That was a guess actually... it was ...'
'Come on.'
'I don't mean to be rude...'
'Go ahead, I don't mind.'
'You're dressed like a teacher.' He meant shabby.
'I am San Cassimally,' I said.
'My name is Dave,' he said, 'Dave Watson.'

(I made the last bit up.)