No problem, ask all the questions you want none of them are silly.
You can mix as many brassica's, winter peas, or anything you want when you seed in the fall. A problem you might come up with is some of the brassica's need a summer plant date rather than a fall plant date to get bulbs. I personally don't do turnips anymore for a variety of reasons, but I do plant radishes in my fall mix for their leafs/tops. A second problem might be wanting to terminate the brassicas the following summer before they go to seed. Doing this without killing your clover could be a challenge. Just to be clear... I plant tons of things in my mix. It's not just wheat, rye, and clover. I'll plant 10 to 15 species sometimes just to have diversity. Some of the things I plant get out competed and never present themselves. Some of them don't appear to be there until summer stress when others struggle and they get a chance to emerge. I'm going to tell you this... it's not a exact science, you almost can't mess up. Research some plants, ask questions, plant things and have fun, pay attention to the results and go back to the one's you like. The only way to screw this up is to introduce or allow an invasive onto your place. I only buy certified seed, no bin-run stuff for me (except for black sunflower seeds, they've been clean for me). But as far as planting the wrong thing for deer or messing up a mix, I don't think you can. You might check out Greencovercrops smartmix calculator. It's pretty fun to play with and get some ideas/guidelines.
SmartMix Calculator
I do this mix every year. I don't have to, the clovers will either be perennials that come back for several years or annuals that can re-seed themselves.