Wallflowers are of the genus Erysimum, Gattina, and are normally in shades of yellow/cream. They are easy from seed and various species would be available from seed merchants such as Plant World Seeds:
http://www.plant-world-seeds.com/store/flower_seed_categories/ERYSIMUM_SEEDS
When I started this response I expected to easily give several suggestions such as Chase and T&M. T&M just seems to offer mixed wallflower varieties and Chase has disappeared. Does anyone know if Chase Seeds still exist, they used to be a very reliable supplier?

I have been told that Erisymum chieri - the biennial wallflower, can be sown from seed - in fact I grown them every year, Bulba, but the perennial one, which is the one I want, can only be grown from cuttings. Relatively recently, they've both been classified under the same name of Erisymum, which makes it very confusing. I haven't heard of Chase, and I refuse ever to buy anything from T&M again!

Sorry, Gattina, but the perennial Erisimum can be grown from seed - that is what they do in nature!

I'm at a loss to know why I can't find much seed of it then, and it is often described as "Effectively sterile" There ARE seeds available, but they are expensive and I can't find many varieties.

This year the SRGC seed exchange listed 23 different species of erisimum seed. The 2012/13 exchange is just about to close but left over seed will be available at the 'Early Bulb' day at the end of Febuary. If you like I will see if there any erisimum seed left (all seed are in short supply after the poor summer) and take some for you. If successful I will contact you for a mailing address.

there are many named varieties, look at spritzhenry's plant profiles to see which ones she grows. I grew winter sorbet expecting it to be white and it wasnt. nice non the less.

Hallo Gattina - it was 'Winter Moon' but sadly, it didn't survive the winter. I was silly - I didn't take cuttings off it. It was a beauty, and if I ever see any more I shall buy them...and this time, cuttings will be taken!

Oh that is a shame Spritz. it is a lovely plant.

Oh Spritz, what a terrible shame! At least I at last have a name to look for. I've had a look in your plant profiles, and that's the one!

Good - pleased I could help. :-))

Hi Gattina, Hayloft plants will airmail you plants. They have a very pale creamy white erysimum - 3 plants for £12.00. I have not used them but members do mention them from time to time.

Scotsgran - I have just had a browse through Hayloft's catalogue, and this is absolutely what I needed! Thank you so much!

Just be aware that the plants will be very small - plug plants, really. Good luck with them!

I know, Spritz - it's a big drawback, especially getting them out here to Italy safely. If I get them sent to my sister-in-law in the UK and get her to plant them up for me, then I can collect them when I come to visit and whisk them back in a suitcase. You have no idea how much stuff makes it out here courtesy of a stout polythene sandwich box, some damp newspaper and British Airways. I daren't allow them to suffer at the hands of the combined Royal Mail and Poste Italiane: most of the time things get here remarkably quickly, but one Christmas card once famously took 8 months to arrive. :o( I don't have much choice, unfortunately.

Bulbaholics offer to get you some seeds would probably give you plants in the same time scale as your complicated delivery arrangement.