It's not a stupid question at all. You can still plant fast-growing stuff that you can pick this season - radishes, lettuces, spring onions. You can also plant stuff now that will overwinter and you can pick next year, such as onions, spring cabbage, garlic and the like. You can also plant some stuff that you should really have planted last month and just hope for a long summer, such as peas, spinach, carrots etc. Maybe they'll ripen, or maybe you'll get a frost before they're ripe but it can't hurt to try. And then you can get down the garden centre and buy some plants that have already been started off so you can plant them out and it will be "as if" you planted them as seeds a couple of months ago. As to what that will be - you'll just have to go to the garden centre and have a look what they've got.