It is likely one of kukri snake species, but quite hard to tell which from this view. Some species are very variable in color. Do you have more photos with side/top views etc to post? It may also help to exclude certain species if you tell us where you have seen this specimen, some species are quote local to certain areas.
Kukri snakes are nonvenomous. When hold they may bite, they have razor sharp teeth naturally designed to crush eggs.
Looks like Oligodon fasciolatus, Small-banded Kukri Snake. It's hard to count the midbody scale rows in this picture, it should be 21 rows to confirm it's the Oligodon fasciolatus.
Most snakes can 'rattle' the tail. Same purpose as Rattle Snakes, only is the tail not evolved in a rattle in most snake species.
Quite a few snakes also use the tail for caudal luring. Basically by imitating a worm with their tail they try to attract geckos, lizards or birds to lure them within striking range. Not sure if Kukri Snakes do this, though I have seen this species eat lizards, so it could be.
Kukri Snakes sometimes coil their tail up in the air when threatened and showing the ventral colors. In the species in your picture this is most likely not a striking color, but some species have bright colored undersides.
And a good lesson, never to put your hands under a piece of debris in Thailand. in this case it would not have caused much else than a nasty bloody bite wound (for the reason Rushen mentioned, Kukri Snakes are some of the worst non-venomous snakes to be bitten by.).
But it could have been something more serious like a cobra, krait, or viper.
Just for your information in case you want to minimize the chance of snakes in your garden, it's best to keep the yard tidy, don't leave any debris behind, and the larger the mowed lawn, the less snakes. Of course it is not a 100% guarantee, but in general snakes do not like to move around in open areas with no place to hide. Crossing a lawn would be very risky for them as it makes them easily visible for birds of prey etc. Yes (many) snakes do like open areas for basking, but usually they choose an open spot directly at the edge of some thicker vegetation where they can hide whenever they feel threatened.
Thanks for the info. Several Thai people said it was called a 'Hung Gading' or 'shaking tail' and they say it's very dangerous. So I'm a little unsure?
Thanks for the advise to keep snakes away from the house. I know about turning things over, so was careful. We have a lot here, including a King Cobra that wound up in the kitchen. After that episode we cleaned things right up, but we've slipped behind lately. Lots of trees helps keep things cool, but lots of leaves.
There seems to be a lot of snakes around lately. Maybe chasing the last of the frogs?
Haha, yes, it's sometimes funny what the locals come up with in terms of snake ID.
I know only a handful of Thais that know how to properly ID snakes, but 99.9% of the locals can not even ID the most common species (as proven by the Ngu Krading ID they gave you. Ngu Krading is the Thai name for Rattle Snake and there are no Rattle Snakes in Thailand, only on the American continents.). There is LOTS and LOTS of false information, and even park rangers often are not able to properly ID snakes. And you can not blame them , pretty much all of the snake field guide books are full of mistakes. Not to mention that there are new species described each year. This year we have found a few that still need to be described. The herpetofauna of Thailand is not even closely as well documented as e.g. the birdlife.
And talking about misidentifying.
Even the professional herpetologists make mistakes, sometimes disastrous mistakes. Try to google the story of Joe slowinski (ok not in Thailand, but in Myanmar), but his team member misidentified a little snake as a wolf snake. handed it over to Mr. Slowinski in a bag. Mr. slowinski put his hand in the bag to grab the snake to have a closer look. He gets bitten, and finds out it was not a wolf snake, but a krait. He did not survive the incident.
In Thailand one of the foremost herpetologists published what was supposed to be the first record of the Many-banded Krait, Bungarus multicinctus. The photo of the find was published in his book. However, the snake turned out to be a wolf snake. Oops, quite a shocking mistake by an established herpetologist, but at least better to consider a harmless snake to be dangerous, than the other way around . But he was right that there could be Many-banded Kraits in Thailand even though they had never been recorded. Because a few months ago, I went on an expedition to Northern Thailand with two friends that are both very much into herping and we found the real first record of the Many-Banded Krait in Thailand! That is the 4th krait species known to occur in Thailand.
But anyway, that's how hard snake ID-ing can be. And it's a shame, because locals often make these mistakes and this means lots of snakes get killed because considered dangerous, but actually they are harmless.
Also in many cases the 'King Cobras' that the locals have seen turn out to be one of the large rat snake species, or one of the 'true' cobras (King Cobra is in a different genus than the other Thai cobra species).
Sometimes Kukri Snakes are confused with Malayan Pit Viper (Ngu Gapaa) or Siamese Russell's Viper (Ngu Maew Sao). These two species are very dangerous, especially the Siamese Russell's Viper (my avatar pic )
Currently, I am working on a webpage where I intend to show all Thai snake species and hope in the future to show all details of each snake to make identifying easier. I only recently started with this project, so still have a LOT to do. It is a hell of a job, haha.
I will give the link of the Siamese Russell's Viper-page as an example, one of the few species I have completed including detailed shots). My plan is to 'do' all vipers first (though there are still quite a few I have to find first...)
Here's the link.
This is the Russell's Viper that people often confuse with the Kukri Snakes. They are very different if you look up close, but for many people it's just a brown snake with some markings on the back, just like kukri snakes can be brown snakes with markings on the back.
There are a few other species on there, with pics, though info is not complete yet. So far all three pythons are on there, 3 of the 4 cobras, 2 kraits (including that first Thai record Many-banded Krait), will soon add the other more common krait, the Blue Krait, also known as Malayan Krait, bit similar looking like that Many-banded Krait. And lots more will follow as soon as I have some more free time.
But at least you can now try to teach those locals that the snake you found is NOT Ngu Krading. Kukri snakes are in Thai called: Ngu Peen Kaew. But it's not unlikely that they have never heard of this Thai name, haha. There are quite a few Kukri Snake species in Thailand, and various new ones to be described. All are harmless, apart from that bloody bite wound...