Just the American over here in the corner googling “hamper”. When I was growing up in the US, the only hamper I’d heard of was the covered bin for dirty clothes. Seemed like an odd gift for travelers. 
Now that I’m informed, it sounds like a lovely gift and very thoughtful of you to think of the sitters.
We had a lovely lady put up a tree for us last Christmas on Mallorca and the wonderful friends we are doing a repeat sit this Christmas on Crete will be decorating for us, too!
Dan and Nan
I think I learned what a hamper was from Harry & David catalogues or such, for holiday gifts.
How lovely. I’d be delighted with the hamper, but as I don’t really do Christmas, I wouldn’t want you to go to the trouble of decorations just for me! But then of course everyone is different…
We’re mostly vegan, and we would love things like vegan chocolate, posh crisps, nuts, halva, turkish delight, satsumas, ginger wine, a little liqueur bottle or two from Lyme Bay… any of the above, really… and now my mouth’s watering! 
We decorated early as we will be gone from early December until right before Christmas.
We also bought a couple Advent calendars for our sitter to have fun with while here.
We did a sit during Thanksgiving in the US last year, and during Christmas in Australia. For the Thanksgiving sit, the homeowners left us a very nice bottle of red wine and a goodie bag with some delicious crackers and cookies. For the Christmas sit, the homeowners did not leave us anything, but they did have a small decorated tree which was nice.
We never expect anything, but always appreciate when homeowners leave a little something. We’re easy to please - no dietary restrictions and we do enjoy wine, but I realize others may feel differently. The most thoughtful homeowners asked us prior to our sits what they could get for us. I didn’t feel comfortable asking for much, but one homeowner did a little bit of shopping for us and left fresh berries and milk at our request, plus filet mignon and wine as a surprise for us. Another homeowner made us a home-cooked dinner and left us two very nice bottles of wine, plus told us we could consume any of their food we wanted (which we replaced).
If you are in the uk, many independent shops and supermarkets have vegan treats - including interesting cheeses.
How thoughtful! I’m sitting over Christmas (my first sit!) and have begun collecting goodies to take with me - I have weird food allergies (whoever thought rice could be one?! And it’s hidden in so many things!) and so I suspect I’d not be able to eat a lot of what a well-meaning host might leave me, which I’d find awkward (but I’d feel touched that they’d gone to the trouble). I’ve already asked the HO for freezer space for the Cook dishes that I’m treating myself to (note for non-UK readers: Cook sells frozen, home cooked luxury ready meals)
Maybe mention your thoughts to your sitters and see what their response is?
Thanks everyone for all the replies
So I have checked with the sitters, they do celebrate Christmas, no food allergies, will eat anything so here is what I have on my list :
Oh my sounds like heaven
@MigeyMeatball - that sounds so considerate and generous.
I am sure it will be appreciated by your sitters.
I alway appreciate a Xmas sit where the home has been decorated.
Please elaborate on the whole “Hamper” thing. I don’t see the answer to the question of what it is??
@Lisabentson7, it’s the kind of gift basket that you typically fill with fruit, treats, baked goods, cheeses, jams, chocolates and other candies, maybe alcohol. Or maybe fancy bath products / toiletries or candles. They’re usually picnic baskets / wicker baskets with lids.
In the U.K., these are higher-end versions: https://www.fortnumandmason.com/hampers/all-hampers.
F&M are well-known for their hampers, but of course you could fill your own along whatever budget you want.
Thank you Maggie, that is what I was assuming after reading all of the posts.
My husband and I (together and separately) have received many hamper-type gifts over decades. Every time, stuff goes to waste, because it’s not to our taste. To me, I’d rather give or receive a gift card that allows the recipient to choose what pleases them.