I found the answers in another post.
The Bean crosses would be rare.
But the squash and the pumpkin can cross easy.
The others can't cross.

If I am not mistaken the gourd can also cross with the squash and pumpkin and probably the watermelon.
James

no the watermelon will not cross with anything . The beans can cross with each other but they are inbreeders so it would be uncommon. Ornamental gourds will crossbred with pumpkins and squash . but I do not think bird house crosses with summer squash , Maybe winter squash though. and the squash and pumpkin can cross breed .

Can a mustard seed be cross with any other seed?

grhrtn, mustard is in the large Brassica family. I don't know what it will easily cross with, but the family includes broccoli, cauliflower, brussels sprouts, kale, radish, and cabbage.

It won't breed easily, but there is even an effort at the University of Idaho to cross mustard with canola to get mustard's good growing characteristics with a higher quality oil.

Here is a link that might be useful: Encyclopedia: Mustard

As far as pumpkins and squash this is a site that I found when wondering what I can cross some Atlantic Giants with. They are C.Maxima, but as you can see at the end of the report it shows the species and cultivar. I am not a geneticist, but I believe you can cross plants in the same species. So take a look and see. Look to the end of the article as it is a bit drawn out for your purposes.

http://www.ars-grin.gov/npgs/cgc_reports/squash95.pdf

Here is a link that might be useful: squash report

Cultivated beans can self-pollinate, but will cross if given the chance. If we raise only one strain, the crossing isn't apparent.
W J Beal raised crossed wax beans back in 1879, and noted their superiority over uncrossed plants.
http://www.bulbnrose.org/Heredity/Beal1879.html
Karl

Here is a link that might be useful: CybeRose & Bulbs

Here's an interesting article describing which cukes, squash, melons, pumpkins etc. can and cannot cross.

http://www.walterreeves.com/food-gardening/squashpumpkincucumberwatermelon-pollination-explanation/